I ordered my AD900s a week ago and they sound great.
Wasn't wowed by them, but that's probably because lurking on head-fi built up a lot of expectations, and the source I'm using (mp3 320/v0/flac out of some standard dell sound card) is probably a massive bottleneck. I mainly listen to rock/metal, and the bass impact wasn't hard to notice, which was a pleasant surprise. Mids and trebles were a considerable improvement over the JBL reference 510's, but I can't help but feel like I'm hearing sibilance at times. Again, maybe it's my source, maybe it's still burning in.
As for comfort, they fit pretty well with me, even with glasses on. The velvet pads are soft, but they do exert a bit of pressure over time, and can get a bit warm. I was pretty lucky that my head is neither too big nor small, and the ad900s do get mention of how they slip off easily for people with small heads.
Hope that helps