Windows Vista is an ok OS, but in the end, doesn't really offer much more than XP does. Most of what I've seen is just flash and fancy, very little substance. Some of the default security settings are a bit too much in my opinion, but that's just me.
It's not at all bad, but for the price, and the fact that, in my opinion, it doesn't offer much more than XP, it's not worth getting for a long while.