QFT. Totally unfair evaluation.
If all you are doing is running standalone to play games or light home usage, Vista can be made to work. If you use it in an Enterprise environment & ask it to interface with a network and multiple business apps, its many flaws become apparent very quick.
None of my clients have a compelling need to upgrade, so I am recommending staying with XP for the forseeable future.
I run all our line of business apps on Vista. Granted the standard desktop image is XP, but I have Vista on my machine with no problems and I'm lovin it!