Pros: Outstanding build quality and accessories. Fairly balanced frequency response and good sound quality which improves with basic amping.
Cons: The lack of the usual treble peak makes the sound a bit dull for some.
After spending some time speaking to Val, the owner of V-MODA, in Tokyo, he send me a pair of these to evaluate and give feedback on. I reckon if Apple made headphones, they'd turn out something like these. The attention to detail in the design is fantastic.
After Tyll Hertsens wrote his review on InnerFidelity, I'm at a loss as to what I can usefully add to what has already been said by him, as well as everyone else.
The overall sound-signature isn't as bright as many other headphones, lacking the usual treble peak found between 6-10 kHz, so they sound, to me, a little "thick" and muffled. However, Val made an interesting point, that DJs who use models with that treble peak often end up losing their hearing in those ranges as DJs listen LOUD. So while the sound signature doesn't entirely agree with me, it does make sense for younger people who buy them who are likely to turn up the sound quite a bit more than I do now.
I did EQ in a treble peak in iTunes (on my Mac) or EQu on my iPhone to get an idea of their ability as headphones. Giving the 4, 8 and 16k sliders a bit of a boost helped especially with classical music which works better with brighter headphones.
While they sound good out of my iPhone they benefit from the use of an amp. I took them along with me with my Fostex HP-P1, which improved the sound noticeable, primarily in that some harshness that is present out of an iPod was no longer there. I'd say though that the Foxtex is overkill for them ($7-800 vs. <$200 for the M-80s). It'd be interesting to nail down where the price sweet-spot is with amping as I think my iPhone is fine as a source, just needs a bit better amping performance. My MacBook Pro, on the other hand, seemed about spot-on.
Back when I registered on Head-Fi, the pads on my MB Quarts had gone flat, so I was looking for a new pair of headphones. They had cost me almost exactly the amount you can buy the M-80s for. Listening with the M-80s out of my MacBook Pro now, I wish they had existed when I first joined, as for the music I liked then (pop, rock and the like) they are spot-on with sweet vocal performance for a relatively inexpensive pair of headphones.