Vista certainly does have eye candy, and I would say its the most prominent and obvious feature and change in the OS. However, after using it for over a week now, there are tons of little things that make life so much easier. Going back to XP on my laptop everyday at work makes me want to buy a copy of vista for it... For example, being able to just search the start menu and any folder and have it dynamically update the contents is super handy. The feeling of the whole system is better too, everything feels smoother and more responsive than XP does and its not just because of the smooth animations that vista has.
There are many more parts of the OS that feel great, and the points you bring up about performance are valid, but XP wasn't in any better shape when it first launched. Give it 3 - 6 months and everything will be peachy for most users.