Vista keeps getting better! Sure, there are still many bugs and improvements to be done, but this is a very stable work, and we're doing all our WPF experiments in Vista now.
Setup still managed to erase my Windows XP from the bootloader, and had to do the same thing as with the previous CTP. But other than the experience has been very good.
There are some neat new graphics - especially the Aero cursors now on by default!
I also noticed that the performance of WPF applications is much better on this build. There is a small glitch with ExprID and Vista, tho. Unless I disabled Desktop Composition, the menus dont show or rather don't draw.
I highly recommend trying out this build!