Look none of use really knows but from what I read from people who have played around with the beta this is what I have gotten.
1. It is an upgrade from XP and is better.
2. It is no where as good as it could have been. Microsoft promise a lot of things at the beginning and many of them was taken out of the design.
In conclusion is it a improvement over XP yes but is it as revolutionary or even as close to as good as it could of been no.
Here an article that a bit negative about Vista but I think it shows why Vista is not as big as improvement as it could have been.
Personally I plan to eventurally move to Vista but I dont have high hopes that it going to totally change how I think about operating systems.
I dont think it as big of jump as it was from moving from windows 3.2 too windows 95.