After listening to these for a week (just now getting off a cold, but regardless) I am enjoying them quite a bit. A huge thing I've noticed is how they scale with better equipment. Running them from my Clip+ or iPod Touch is fine; they reach sufficient volumes and the sound is decent. However, they really shine when using them at home with my CKKIII and TPA Opus. For instance, with the portable devices the treble can be harsh and if there's a hint of sibilance in the song, it'll be intensified to the point that I simply can't listen to some songs. With my home gear, the treble is beautifully smooth and refined.
I know a lot of you who have tried these and posted your impressions have also tried a lot of other higher end headphones and amps. Maybe these are just picky about what gear matches well? I think they sound great with my home equipment and I can't hear the hot treble that some of you have mentioned. I do not have the experience and caliber of equipment you guys do, but I might just be lucky to have stuff that suits well.
Also, the bass isn't as exaggerated as I was expecting. It's there when the song asks for it, but so far I haven't once felt it was somewhere it should not be.
Vocals are fantastic; I'm especially enjoying female vocals with these.
Soundstage is not huge, but I think it does a pretty good job with positioning. Soundstage isn't very important to me, though I don't mind a wide and deep one at all. Classical is listenable, which to be honest I was expecting I would never use these for prior to buying them.
These impressions are mostly with respect to my HD580s and IE8s. I'm working on a more in-depth review that I'll try to put up on the product page within the next few days.