i purchased them as well and received them today.
i came from ATH-M50, DT770 pro 80, and triplefi 10s. I use a Fiio e10 right now.
before i get into sound, i can say comfort wise, they have far more clamping force, and the headband pushes down on that sensitive point in my head. I can feel it immediately which is definitely a negative in my book. The dt770s i wear all day (8+ hours at work) without problem. The ath-m50 fatigue the crap out of my ears after 4-6 hours, to the point of having to take them off fully. The triplefi 10s with the comply fits start to bother me around the 6-7 hour mark, but i make it through the day with them. With silicone tips I gotta take them out after 4 hours; mind you, I take them out rather frequently throughout the day as is.
initial impressions (literally listening to them for 20mins or so, so clearly they aren't burned in and i heard it helps them heaps). damn, these are cold as ice. the bass is way more focused than the dt770 80s. the 770s have much more boomy bass and these are dont rumble as much but are pretty damn punchy. The V sound contour offered by these seems to be more exaggerated than the dt770s. I can completely understand why these are a love or hate pair of headphones even after an initial listening. They completely expose any track that isn't mastered properly, as well as low quality music. The 320kbs stuff doesn't sound nearly as good as FLAC (much more noticeable than the dt770s). The highs are slightly harsh for me at the moment, but i hear they are tame after burn in. I really hope so lol.
Music I listened to:
16bit - Frz9000, dinosaur, swine flu. 320kbs. They sounded fantastic.
pink floyd - shine on you crazy diamond pt2 320kbs doesn't sound that great. I'm gonna give the flac version a listen later to see if i notice any change.
florence and the machine - shake it out 320kbs. wow...the vocals sound amazing. the shaker really comes out, and the drums sound great. match made in heaven for the pro 900s without even burning them in.
noisia - tommys theme 320kbs. sounds pretty flat until the drop...when the bass comes in, the song comes alive. holy ****. if you like dubstep, you gotta hear this lol...
danger doom - benzi box, the mask. flac. damn, these things pick up even the tiniest of static in the background of the track. the V contour sounds is pretty evident here. mids are crazy recessed but the vocals over the bass sounds great.
I used bass boost on and off on the e10. With bass boost on, you can tell that the bass is exaggerated and not natural. With the dt770s, its harder to notice the effect (in terms of fakeness if that makes sense). I will try to do a full review and comparison of my headphones after I get 200-300 burn in hours on these.
So far i'm pleased. I really hope I don't have to sacrifice comfort in the long run for this sound.
i can't wait to hear them. i am giving my dt770 to my newly promoted assistant so i need a new closed can to take its place. couldn't pass up on that deal. my next purchase will be a schiit bifrost for my birthday then i'm done for awhile lol... but that's what we all say 
