I tested Vista RC1 and some of the betas and i can say it isn't worth the money (yet).
The looks are fine but the way MS new OS lets users take control of their machine isn't that.
Maybe in a business environnement Vista will have some purpose, but not for home users or professionals who are used to have full control.
On the other hand, MS has made Vista more attractive with the Aero Glass feature and the new looks. I like XP the way it is and it will take a very, very long time for me to change to Vista. But a new look for my XP, why not ?
(And i'm sure i'm not alone in thinkin' this way)