Hi have a pair of those. They're very nice to listen to them, warm, good bass out from the box, if anything a bit lacking air, detail and spark on top. They need a lot of burn in to bring out the midrange and sound really coherent, and when I mean a lot, I'm speaking of several hundred hours and using really stressing material, not the typical pink or white noise, but bass heavy tracks with agressive percussions in it.
They are not the most comfy HPs, the headband clamps pretty strongly, as in all Ultrasones, the earpads are a bit too small for my ears -and I'm not a big eared man- so the HPs stand on them and create some pressure and heat, but the velour is good and is not really disturbing.
Sound is good enough to listen any music, and I found them really funny to listen to movies, speech is clear and their generous bottom is good for explosions, quakes and all that stuff. They do fairly well with pop, rock and rhythm based music, pretty fast and "Pratty". With well recorded acoustic music they show more their flaws, and you might be missing some detail and refinement. In any case they're way more relaxed and easy to listen to than the 750 or 2500, and probably less agressive and a bit more laid back than the new HFI-780, but I haven't listened to these and my references are for what I read on the current threads going on here.
Had you more specific questions, I'll be glad answering them. Regards.