What pkell said...
Sometimes it seems that most of the people who seem to hate Vista only do so because it's not XP (can't help you there...). Or because their ancient box won't run it (don't upgrade an old box). Or because they can't find drivers for the ancient component they've run for forever on XP (component maker's responsibility). Or because of unstable drivers (again - the component maker's issue) Or because their 10 year old game doesn't run on it (I love Planescape-Torment, too!!). Or whatever...
A more blunt answer is if you're not comfortable running Vista, then don't. From a user perspective the differences aren't all that great - DX-10 and a flashier interface, basically. And the layout is different, so you'll have to re-learn where a lot of things are. This last point especially seems to piss some people off to no end.
If you're building a new box, from new components, and are willing to refer to the manual now and again to figure out where MSFT put something, then you won't have a problem.
My experience with it is that it is about as stable as XP, that it's a lot more aggressive about managing system resources, and that I lost a whopping TWO frames per second in gaming.