Windows Vista SP1 hit yesterday and I immediately installed it on my home machine and work laptop. I really only had one big gripe with Vista, that being the speed of file copies, both local and remote. Once I applied the update, things greatly improved. I would say it is now on par with W2K and XP, although I don't have any statistics to back this up.
I'm sure I'll be reading about how awful SP1 is, or how bad Vista is, but I have to be honest -- I do not agree with what I've been hearing. I've called a few people out on their gripes and they admitted to never even using Vista.
This weekend will be a good test for SP1, as I will be in Massachusetts upgrading some servers.