Ok. First impressions:
Comfort-Wonderful for short listening, but they hurt for longer sessions, just be because they're on ear and they're brand new. Clamp is just right.
Isolation-Nice, no complaints
Build- Nice, wonderful actually.
Concerns- Only one problem, and this will suck for some people, is the microfonics. Rubbing the cord at lower volumes isn't a pleasant exp, and any touch on the headphones will produce some sound. The cord is a little thin.
Sound- I shouldn't write anything on the sound really, its too early. But I guess I could say something. The sound is pretty much neutral, though having a veeeery small bump in the upper bass/lower midrange area. The highs thankfully aren't recessed, and the bass is absolutely perfect quantity wise. Like beagle in the m500 thread said, the quantity of bass depends entirely on the recording. Some are bass light, some bass heavy.
Quality wise, I won't give many impressions. I'll say they're very clear and airy sounding (compared to other portables in this price range). The soundstage is pretty damn good for an on ear too.
Only good things! Against the ws99, 1r, etc, well that'll have to wait for another time.