I have no problems with it as well.
If you have a machine that can handle it properly, then I think it is nice.
Visually, it is a big improvement. Some of the new features are nice too, such as the search bar.
While my upgrade went smoothly a lot of people seem to be having issues with drivers, etc. I would check tomake sure all of your drivers are available for vista first (vid. card, sound card, printers, wireless, etc.).