I was using 64-bit RC1 before I got my copy of Home Premium, so I'm kinda used to using it now. I find it a lot better than XP - not sure why that is though. It just feels better, everything seems a little more intuitive, all the useless menus are out of the way and all the stuff you need is right there. Theres no hunting through directories trying to find the right one, because they seem to be nicely placed (e.g. Personal Documents - where the hell were they in XP? Like, 10 folders in!).
Loving the new Media Player. I spent about 5 hours just arranging all my MP3's and getting the album art for them. Pointless I know, but when you have Vista which looks so nice, you sort of want everything else to look good too.
I had a few problems with games in the RC1 release, but since installing Home Premium and grabbing the 7.1 ATI drivers I haven't had a problem with anything. City of Heroes, Half Life 2, Counterstrike Source, etc, all runs fine, no noticable drop in frame rates as far as I can see.
I installed it early mainly because I'd just upgraded to a new system, so instead of going through the trouble of putting stuff on XP then having to reinstall over the top of it sometime later, I jumped straight into Vista. Something I'm not sorry about.
-- The Unusual Suspect
System: 2.4GHz Intel Core 2 Duo, Gigabyte 965P-DS3, 2Gb Geil DDR2 RAM, 2x250Gb HDD in Raid 0, Creative Audigy ZS Pro, ATI X1800 Graphics Card.