I got Vista 64 on its release and haven't looked back. Using XP since?... I can only describe it as that icky feeling as an XP user gets going back to something like 98, it looks pretty similar, everythings in near enough the same place, but its just clunky, unpolished and all of a sudden horrible to use.
It's already been shown that most of the problems with vista have been driver related and most of those are nVidia's fault. Then theres that "well my gamez runz better lolz" arguement, well I distinctly remember when XP came out people saying that about 2000, that XP was bloatware and games run slower than existing versions of windows, you've all changed your tune now.