Pros: Sound can be excellent, depending on the source. Price is the best value to be found.
Cons: Fit and seal can be difficult. Cord is kind of strange, looks GREAT but is actually kind of stiff and kinky. Needs a neck slider.
I bought these cheap 'phones because of all the hype I saw on Head-Fi. The hype is so well deserved that I registered to Head-Fi just to add my weight behind these earphones!
I use these on my Sansa Fuze+ player and they sound absolutely excellent! With a good seal, which admittedly is difficult to get, the base can rattle your eyeballs....... NO KIDDING...... I was amazed.
My gold standard for "phones is the Koss Porta-Pro, And the various formats using that same drivers. On my Sansa Fuze+ the Porta Pros sound BREATHTAKING.... But I actually prefer the Monoprice over the Porta-Pros. There is an over-all pleasing and satisfying quality to these "phones that is difficult to explain. The sound is different than the Koss, Since the Koss are PERFECT, this would indicate that the Monoprice is inferior. Even so I consistently reach for the Monoprice and am extremely satisfied with the sound. They are more efficient that the Porta Pros Too.
Now to be fair I also own a Sangean DT_400W pocket radio. This is a VERY high quality radio and the sound is WONDERFUL in headphones........ Except these Monoprice 6320s sound harsh and middy with that radio. The sangean's BassBoost switch only adds boominess to the mix. I would love to love the Monoprice on that platform also....... But no, the Porta Pros are the only way to go there.
For the $8 you just can't beat these "phones! My Koss cost $35 ON CLOSE OUT SALE, yet the Monoprice are every bit the equal on some platforms such as the Sansa player. The Monoprice will take amplification to the point of pain, in spite of the better efficiency...... I just don't have amp enough to make these drivers clack bottom. I can overdrive the Koss with the same amp.
If you don't like these 'phones then you didn't get a good seal..... Or your device just doesn't drive them well. The good reviews are ten to one against the bad ones. Buy some Monoprice, They are excellent. If you don't think so, just save them. Another platform will show them to be the (ugly) little jewels that they are!
UPDATE! - 2/19/16 It's approaching two years since I reviewed the Monoprice 8320 . I am listening to them right now. The cord is all kinked and crinkly, The inside wires are poking through the fabric in tiny loops here and there. They are sporting triple flange MEE Audio tips now, for a quick and reliable seal. Looking rough and sounding WONDERFUL, they are in daily use and still going strong.
Mike Oldfield's Tubular Bells........... That low organ pedal note just rumbles, a note nonexistent and not reproduced when listening with full size speakers by the way. Freakishly clean tinkling highs...... Well...... Just like the ringing of bells! Let's not neglect Pink Floyd's Dark Side Of The Moon............ The heartbeat, WHUMP-BUMP.....WHUMP-BUMP.....WHUMP-BUMP, gives chills and goose bumps. The clear and pristine voice of the torch singer on The Great Gig In The Sky brings tears and you don't know why. The clinking of coins onto a table so accurate that you instinctively check your pockets for spilling change. Can you tell that I really love these earphones? The best $8 ever spent! Still going strong what, 20 months later? You can't beat that.