Pros: Build quality, great balanced sound quality, beautiful carrying case
Cons: cable could be more flexible
When I received my M-80, the first thing I noticed was the premium packaging. Build quality is really great, these headphones have really a premium feel. Also the case is unique. 2 cables are included, one with only mic (compatible with most phones and players) and one for apple products. The cables are a bit stiff, I don't know if they will become more flexible with usage.
After 24 hours of burnin, here are my considerations about sound. Currently I own also sennheiser IE8 so I will do a little comparison.
Differences between IE8 and M-80 sound signature are not too big. Both have a warm sound signature. M-80 has deeper, more controlled and more detailed bass. M-80 bass is more real and doesn't sound as "close" (like being in a cavity) as IE8. M-80 mids are wonderful and really smooth and don't have that veiled sound caused by mid bass peak as the IE8. M-80 mids detail > IE8 mids detail.
Highs are normal, not harsh, not sibilant at all. They are similar to IE8 ones with a bit less detail.
Sound stage is obviously bigger than IE8 as it's a headphone.
In conclusion, it's a great headphone for the price. I think it sounds better than IE8 over all, so I'll use it as my main headphone and IE8 when I need ultra-portability. What I like most is that it sounds really lifelike, not artificial and I can't stop listening to it.