Whilst I don't exactly agree with some of the things Microsoft did with Vista, I've had it for a good half a year now and never had any problems whatsoever. I was sceptical at first when the salesman told me it came with Vista and no way to get it with XP, but now I couldn't live without the weather miniprogram on my desktop.
I was told I couldn't run Bioshock without spending 3 days installing fixes, but hey, I installed it and played it without any problems. Jesus christ, I never got it to work properly on my XP machine.
But then again I have a Fujitsu-Siemens laptop which people have been telling me was a bad descision to buy, but again it has not acted strangely whatsoever apart from a slight bug with the nVidia driver which was easily fixed. So maybe I'm just lucky.
All in all, I would say I like Vista more than I liked XP. But perhaps it's just the little nifty things like the miniprograms and the visual upgrade that distract me from the fact that it consumes loads of RAM. Oh well.