I like the Mahjong Titans game.
Seriously, though, I have more dislikes than likes - few are unexpected, however. I got the 64-bit Ultimate, and all of the associated driver headaches - but I was expecting this as one of my computers has XP-64 with the same problems. I did expect the hardware vendors to be more on the ball with Vista, but that isn't the case - but, this situation will improve in time.
I also don't like all of the security measures - the constant prompting about whether you really want to run this program. I also don't like airport metal detectors and screening, but it's a necessary inconvenience - security is security.
The MCE interface isn't like the XP/MCE one. I don't care for it, but it might just be that I'm not used to it. I'm going to give it another week or two in order to judge (I don't dislike it now as much as I did when I first used it, so I want to wait until I am fully accustomed to it before I pass judgement - different isn't always worse).
The Sidebar is cool, but I've used Widgets before - so it's nothing new.
The Aero GUI is pretty, but I have multiple monitors and usually have all of my windows open at full screen - so I don't really benefit from it.
For day-to-day use, you really won't see much different than XP until programs are written specifically for Vista.
For others reading this - if you're building a new system, use Vista since you're going to have to have it at some point anyways (I suggest the 32-bit version to avoid the compatability isues unless you have a specific need - such as using 4GB or more of memory).
If you have a system with XP and are considering upgrading - just wait until you need Vista. By then, the issues should be resolved.