I have seen a lot of improvements in Vista over XP - but I'll have to say that Aero is just a toy that consumes a lot of resources for very little result of substance.
I've primarily used Ultimate with Aero turned off - but I've come to love the Basic version that came on the laptop that we bought for my wife's office. It's lean and clean and does what I want/need it to do.
Most of the improvements (particularly in the kernel, networking, error handling, and in the error reporting) are significant - although they may not be easily seen by users.
This being said, Vista does use more resources than previous versions of Windows. As with any OS, as it gets more "user friendly" it'll consume more resources. It's gotta get more complicated inside so it'll be easier to use on the outside.
Some will live with it, some won't. Only time will tell if it's a success or not.
- John
**If you need a more detailed explanation, please ask for it. I have
the Knack. **