I have Vista Ultimate 64-bit installed for 4-6 months now, I've had 0 problems with it, no compatibility issues, and tbh I prefer it over XP. The majority of people saying Vista sucks are the ones who either, has a out of date piece of shit PC; tried it when it first came out, or has a bootlegged version which does not allow updates. XP was the same way when it came out, a lot said it sucked, after a few updates and tweaks, it runs perfectly now. Quit hopping on the bandwagon of, "I hate Vista cause everyone else seems to hate it" and actually try the up-to-date (including your run down piece of shit pcs) version out right now, then come back and give an opinion.
Not to be an ass, but the majority here are complaining about compatibility issues and lag issues, when I have experienced neither of these since the SP1 update fixed the compatibility issues and since I have 4096 MB of ram to make up for the extra 500 MB Vista takes.
(Basically the same as Trakaill's post)