User 5 months without any problems either in connection or construction. Don't be afraid to go to a company that is not like Sony, JBL, Marshall, etc. Generally, they are worth their money and at ~75 you won't find something so value for money except for some JBLs. The following is a personal (and only) review based on experience.

Positives:
+ Very clear sound, not something amazing but you can hear sounds in music that you don't hear on the phone's speaker.
+ Decent bass if you are a fan of bass like me.
+ Very good construction! It features a plastic that gives a good and premium feel. Along with the metal on the headband and the leather, they are top for this price.
+ The package includes an awesome case with a very hard material ideal for traveling. They also come with a charging cable and a jack for wired connection.
+ Wired Connection! Many Bluetooth headphones don't have it, I consider it awesome +.
+ The headphones, as you can see in the photos, bend and rotate, which was incredibly helpful for me!
+ BATTERY! No one will believe it, but with moderate daily use, the headphones last about a month. Yes, around 30 days, and they take an hour or so to charge.

Negatives:
- After one to one and a half hours, they personally bother me. Not that they tire me, but I want a 5-minute break for rest. Personally, I repeat (each ear is a different case).
- I would prefer the on/off button to take less time to activate or to have a switch (a detail, but I would like it).
- Stronger microphone. It is built-in, I know, but it takes 2 more clicks for the other person to hear you well enough.
- Small Charging Cable. As I said, they come with a cable that is quite small. I would like it a bit longer, like mobile phone chargers.
- Bluetooth connection to PC (Laptop). From the classic Bluetooth device search, the headphones were not found, but through -> Settings> Devices> Bluetooth> Devices & Printers (Right Column)> Add Device. Someone who doesn't know this will find it impossible to connect them unless it happened to me. The good thing is that as soon as you open them and have Bluetooth on your laptop turned on, they connect directly after the 1st pair.

Overall, they are generally WORTH it for 75 euros. After market research, I didn't find something so value for money, and their purchase left me quite satisfied.

UPDATE (9-11-2021)
- The leather on the inner part of the right headphone opened. With a little silicone, it's fine though. It should be noted that I take them on trips, buses, etc. so I don't have such simple use.

Having almost 2 years, I can also write my objective opinion.

So, the positives:

The sound is very good, clear and with strong bass, although the high notes are missing a bit. The volume is also very high, to the point that sometimes I just put the headphones on 100% volume and use them as mini speakers.

The battery is endless, weeks pass until I simply leave them to charge overnight.

Excellent connectivity, I always had them on Bluetooth and never lost signal.

Personally, the headphones never tired me, the earpads are very large and soft, which also isolate the external sound very well.

And now the negatives:

Within 2 years, I had to buy 4 different sets of earpads, they broke relatively often and I noticed that they all broke in the same way, meaning the seam opened from the inside. I consider it a design flaw.

The biggest negative is that the headphones broke on both sides where they rotate. The plastic is very thin in these two points and with use, it weakens to the point that it breaks in half. Unfortunately, I tried many times to glue them in many ways, but the plastic is so thin at that point that it doesn't allow you to do much.

These are my experiences from the 2 years I have had them. Very good headphones, I recommend them, but be very careful, especially if you see cracks starting to appear where the headphones rotate.

Almost 2 months approximately from the date of purchase and I feel very satisfied. I use them daily for 2 hours in bike training. I have only needed to charge them once so far. Absolute sound isolation (you really can't hear anything else except your favorite music and without noise cancellation (you don't even need it because your ear is simply shielded inside the headphones). They have a lightweight but sturdy construction and the sound is simply crystal clear. The bass is powerful at every frequency without being annoying (in some frequencies, it tickles your ear pleasantly with the power it produces). And believe me, I know about good sound (expensive, well-crafted sound in the car and a 1200-watt Sony and Yamaha home cinema sound system). They are already loud, but I wish they had a few more dB because I love loud, clean sound. They are a bit bothersome in the heat because you sweat due to the headphone's leather on your ears, but I couldn't stand the annoying itch inside my ears that you feel for an hour as if you're still wearing it. And with Bluetooth and with a cable, the sound is simply incredible. With one press, you have mute... with a long press, they turn off or you adjust the volume on the headphone or call the last number you dialed or change or replay the same song with prolonged touches. When someone calls me, they can hear me perfectly even while cycling. I don't recommend using them indoors where the network signal is weak because it further worsens the poor communication (although it's definitely not their fault). I think they are one of the best purchases and whoever asks me how they are so far, I say only good things. I hope that over time, they will perform well because the company that produces them is a reputable sound specialist company but with reasonable price levels (around 75 euros without shipping). The packaging was perfect (with a transparent film covering the white hard box that contains the round case of the headphones and inside it, the charging cable that goes into the phone charger as well as the cable that connects the headphones to any audio device. Of course, it's in black color externally and I enjoy them a lot on the computer for movies and for my music. It's a very good purchase, I say it again!

I bought them mainly for use on a computer, so I don't have an opinion on the battery and Bluetooth. The sound quality is very decent for their price. I listen to various genres of music, but mainly electronic music and rap. Initially, they sound a bit muffled with all frequencies flat. The only frequencies that need adjustment are between 125 and 500, and they sound crystal clear - clean, deep bass, although a bit weak for my taste (I have increased it by 3db for the music I listen to), without affecting other frequencies. The mid and high frequencies do not distort and do not "pierce" your ears at high volumes like other branded headphones.

They are quite comfortable without exerting too much pressure, and the cushions are of good quality and soft. Additionally, the cushions are replaceable, which is not mentioned by many and is important for some people who do not plan to buy headphones for a few years.

They are a decent choice for the cost, and with so many features, it is difficult to find something similar.

Edit: The cushions ripped in two months and it is not covered by the warranty. Not to mention that I didn't even clean them.

Είμαι κάτοχος των W830BT εδώ και μια εβδομάδα και έχω να μοιραστώ μαζί σας τα εξής:
Κατ' αρχήν να διευκρινήσω ότι ήθελα να πάρω τα Marshall Monitor που είναι σε άλλη κατηγορία τιμής (κοντά στα 155 ευρώ) αλλά εκτός του budget μου... :(

ΠΟΙΟΤΗΤΑ ΗΧΟΥ
Όλα πολύ καθαρά και ισορροπημένα (αν και στη μεσαία περιοχή θέλουν ένα τσίμπημα πάνω 2-3 db για να τα θεωρήσω απόλυτα flat... Στερεοφωνική εικόνα παρα πολύ καλή.... Συνήθως ακούω reference recordings, jazz, κλασική, rock, και δίνω μεγάλη σημασία στο να ακούγονται σωστά αυτά που θέλει ο δημιουργός της μουσικής.... To aptX κάνει εξαιρετική δουλειά και σε αυτήν την τιμή δεν υπάρχουν πολλά ακουστικά με aptX....

Η έντααη του ήχου υπερ-ικανοποιητική (τα δουλέυω ανάλογα την εγγραφή από 70-85% της έντασης)

Τα μπάσα του πολυ καθαρά χωρίς γαργάρες και χωρίς τον "ψεύτικο" ηχο που δίνουν πολλά άλλα ακουστικά για εντυπωσιασμό.. άμα θέλεις παραπάνω για γούστο σου, βάλτα μόνος σου με ένα EQ, μην χαλάς όμως τις εγγραφές από χέρι... :)

ΠΟΙΟΤΗΤΑ ΚΑΤΑΣΚΕΥΗΣ
Στην κατηγορία τιμής του, εξαιρετική... Και έρχεται μαζί με σκληρή θήκη που είναι χρήσιμη και όμορφη....

ΑΥΤΟΝΟΜΙΑ
Εδώ.... είναι ΜΑΚΡΑΝ ο ΠΡΩΤΑΘΛΗΤΗΣ, χωρίς συζήτηση!!! Δεν υπάρχει ΚΑΝΕΝΑ Bluetooth ακουστικό με τέτοια αυτονομία !!!
Τα έχω χρησιμοποιήσει μέχρι στιγμής γυρω στις 30 ώρες και η μπαταρία μου δείχνει ....75% !!!!
Το χρησιμοποιώ σε εντάσεις 70-85% και είναι πολύ κοντά στις 95 ώρες παιξίματος που δίνει ο κατασκευαστής.... Έχουν και ένα καλώδιο 3,5 mm στο πακέτο να τα ακούσεις ενσύρματα σε περίπτωση που δεν έχεις μπαταρία... εδώ γελάμε..... :D ....

ΕΡΓΟΝΟΜΙΑ - ΑΝΕΣΗ
Εδώ, προσωπικά έχω ένα θέμα... έχω μεγάλο κεφάλι και στα δικά μου δεδομένα είναι λίγο σφικτά.... εδώ το Marshall είναι σαφώς πιο άνετο και ξεκούραστο.... μετα από 3 ώρες τα βγάζω για 5 λεπτά για να ξεκουράσω το κεφάλι μου....

ΚΛΗΣΕΙΣ - ΗΧΟΜΟΝΩΣΗ
Από κινητό και κλήσεις από PC (skype) δουλεύουν ικανοποιητικά.... Σε κλήσεις skype και viber από κινητό, αν έχεις το wi-fi ανοικτό υπάρχει θέμα ... μεγάλο... αλλά πάρα πολλά ακουστικά που έχω δοκιμάσει έχουν το ίδο ακριβώς πρόβλημα.... στα δεδομένα ανοικτά δουλεύουν κανονικά.... μάλλον υπάρχει γενικό προβλημα όταν wi-fi και bluetooth είναι ανοικτά στις κλήσεις.... στα playback ήχου και βίντεο, κανένα πρόβλημα....

Στην ηχομόνωση δεν τρέφει δάφνες... δεν έχει ANC (Αctive Noise Control ή noise cancellation) και είναι λογικό... αλλά όταν ακούς μουσική και έχεις ANC ανοικτό αποβαίνει εις βάρος της ποιότητας του ήχου .. για κλήσεις όμως είναι πολύ χρήσιμο... γενικά τα χρησιμοποιώ στο σπίτι μου, οπότε δεν καίγομαι και τόσο για το ANC.... Η χρήση που κάνω είναι για να ακούω μουσική....

TEΛΙΚΑ ΣΥΜΠΕΡΑΣΜΑΤΑ
ΤΙΜΉ 75 ΕΥΡΩ... Ποιότητα ήχου τρομερή γι αυτά τα λεφτά (τα Marshall είναι λίγο καλύτερα αλλά 155), ποιότητα κατασκευής πολύ καλή, στην αυτονομία ΜΑΚΡΑΝ ΤΑ ΚΑΛΥΤΕΡΑ και δίκαια τα περισσότερα sites και reviews το κατατάσσουν best budget bluetooth headphone...... Στα δύο κρισιμα κριτήρια (ποιότητα ήχου και αυτονομία) με αυτά τα χρήματα δεν πάιρνεις τίποτα καλύτερο.... Αν θέλεις ANC οπωσδήποτε, δεν έιναι για σένα αυτά τα ακουστικά... Για τους λάτρεις του flat ήχου, με λίγο EQ θα την βρείτε την άκρη εύκολα... :)

Ελπίζω να βοήθησα....
----------------------------------------
UPDATE 10/11/2019
Ένα μήνα μετά το review μου, σας ενημερώνω ότι:
1- Η μπαταρία είναι ανεξάντλητη!!! Μετα από 38 μέρες η μπαταρία μου είναι ακόμα στο 70% !!! Και έμαθα επίσης, προς ενημέρωση ολων σας και ειδικά του φίλου σε άλλο review εδώ, το μεγεθος της μπαταρίας είναι 1.500 mAh !!! H αμέσως μεγαλύτερη μπαταρία σε bluetooth headset είναι μόλις 800 mAh σε κάποια ακριβά μοντελα από 250 ευρώ και πάνω.... Θα σας ενημερώσω μολις κάνω την πρώτη μου φόρτιση.... :)

Τα ευχαριστιέμαι θανάσιμα.... Μακράν best value for money!!!
-----------------------------------------
UPDATE 21/11/2019
Η μπαταρία.... επιτέλους άδειασε!!! :D
Από 3/10 έως 21/11 ηταν η διαρκεια της μπαταρίας.... ΕΝΤΥΠΩΣΙΑΚΟ...
Και οι ώρες ακρόασης ηταν τουλαχιστον 100 ωρες πάνω-κάτω.....
Η δεύερη φόρτιση μόλις άρχισε!!!! Η αυτοδυναμία που ισχυρίζεται η EDIFIER, ισχύει απόλυτα!

Απλά η ενδιεξη του ποσοστού της μπαταρίας που έδειχνε στο κινητό δεν ισχύει... Ηταν πάρα πολύν καιρό στο 70%, 3 μερες πριν τελειώσει η μπαταρία ήταν στο 50%, και 4 ωρες πριν να σβησει έδειξε 30%.... και μτα το 30%, ξαφνικα OFF... Nα μην έχετε εμπιστοσύνη στον μετρητή της μπαταρίας των bluetooth.... είναι στο πολύ περίπου :)..
Aυτά τα ολίγα... :)

I am very satisfied with this purchase. I wanted it for my desktop PC and since my computer didn't have bluetooth, I paired it with an Asus USB-BT400 adapter and everything worked perfectly from the start.
I listen to music and do a little bit of gaming.
As for the sound, I had to download an equalizer from the internet (the first one I found) because the factory settings had all the frequencies too low. It took me a few hours to find the sound I wanted, but I can say that it will satisfy all the requirements of any music lover comfortably, from booming bass to light notes.
In my personal opinion, they are not very practical for outdoor use, mainly because of the noise isolation. Compared to other brands in the same price range, this particular model falls behind (you can hear and be heard by others).
However, the biggest advantage compared to other brands is definitely the battery life. I have charged them four times so far, and I'm trying to time it exactly (unsuccessfully), but it always lasts around 85 to 90 hours. I have no information about the battery, as nothing is mentioned on the box or in the manual, and it is still very new for me to open it. But at some point, I will because I'm curious to see what kind of battery lasts for 90 hours and why it is not integrated into every portable device.

I bought them because unfortunately, the Marshall Major II headphones that I had purchased on sale are no longer available in their store, and they had to issue me a credit (the Bluetooth button broke and cannot be repaired - according to the Service). So I went ahead and bought these Edifier headphones.
The Edifier ones are over-ear, while the Marshall ones are on-ear.

The Marshall headphones have a very balanced sound, while the Edifier ones have more... I would say mid-range. Their sound is a bit more "hollow". These are out of the box without EQ or anything.
I would say they are more suitable for house/rnb/electro/hip-hop, rather than metal, which is my music. I tested them with all these genres of music.
Their bass is not excessive. It loses some of the treble, but it balances out with a little adjustment.

With the right EQ settings, using the JetAudio Player, I manage to achieve pretty good results for my taste.

They are comfortable and I can use them for gaming, which is why I give them an extra star in their overall evaluation.

Everything was tested with Bluetooth, nothing was tested (on the phone) with the cable.
On the positive side, their battery life is excellent. I have no idea when I will need to charge them for the first time. They have played for at least 10 hours out of the box so far.

One last negative thing I found is the size. They fit perfectly on my head. But for example, on my girlfriend's head, they are loose... I would prefer the minimum adjustment to be a bit smaller.

In terms of build quality, they don't claim to be top-notch. However, for the money you pay, they are more than ok.

After two weeks of continuous use, I now have a spherical image of these specific headphones.
First of all, their price is particularly affordable as there aren't many options for Bluetooth headphones that support Qualcomm's aptX HD standard for 75 euros. This means a very good range (due to Bluetooth 4.2), high bitrate, and reduced audiovisual lag at a price that essentially represents a one-way street.
Their sound is really good. The bass is completely natural, without exaggeration, and fits extremely well with music genres such as pop, rock, metal, jazz, classical music, and Greek folk music. In R&B songs, it easily comes to a pretty good level with EQ. The midrange is clean, not particularly emphasized, and the treble is diamond-like. Overall, I can describe the overall sound as very balanced. For movies and YouTube, they are a really good choice due to their very good midrange and high frequencies.
With the aptX HD standard, listening to flac or dsd files really highlights the music due to the much higher bitrate provided by the W830BT compared to regular Bluetooth headphones.
Battery life, the best battery ever!!! It simply doesn't end!!! I have calculated that from the first charge I did when I received them, I have used them for a total of about 60 hours and they still haven't died. And because I like to listen to music at full volume (80 to 90%), this is truly a miracle!!!
Comfort is excellent for this category. You can wear them comfortably for 5 hours without getting tired. As for the fit, I have no issues because I have a small head and small ears. My husband, who has a big head and huge ears (lol), wears them and has no complaints.
Build quality, again for this category, is excellent. Very good materials, good cushions that offer very good isolation from external noise, aluminum and plastic. At the same time, the weight is very low, so they don't tire you. The package includes many cables and also an amazing and very slim carrying case that fits everywhere.
In conclusion, I am very happy with my choice, as their sound is excellent, the package is complete, the battery is superb, and all of this at a very affordable price. I hope I helped.