I can agree with both sides, Vista does have a lot of cons to it, but seeing as standards today mean you probably should already have twice the hardware to support Vista if you're even remotely interested in the future of gaming, whether on Vista or XP, then you should be fine.
I use Vista, I've had my troubles, but there is already a lot of support and even more people willing to work around it. For people who are bothered the most by the UAC (the annoying messages you get asking you if you REALLY want to open MSPaint), there is a lovely program out there called TweakUAC. It works wonders, I even forgot Vista had UAC after awhile.
As far as game compatibility, some flat out won't work, others you can try with compatibility mode, which is a feature most Windows OS's have had for a long time. Yes, I know it doesn't always work, but it's worth a try.
Really, do we have to bitch every other thread in the forums about Vista? It's not such a big deal, and XP will be unsupported eventually, and you can't really stop MS from doing it, so deal with it.