Well, Vista Beta 2 (build 5384.4) has been out for a week or two. I downloaded the 32 bit version, and installed it on my home PC.

Some screenshots can be found at my photo gallery.

Some system specs:
AMD 64 3000+
60GB hard disk used for vista
Nvida 6600GT

Some gripes:
It takes quite some time to boot, really hammers the hard disk.
The sleep function doesn’t work (it starts to sleep, saves some stuff to disk, then wakes up straight away)
Sometimes it hangs on shutdown
My removeable hard disk just sits there doing nothing.
Outlook 2007 Beta will consistently crash when I try to inspect an SSL certificate used to encrypt my IMAP traffic.

Other than that, its very pretty. Thats about the only advantage I can see over XP.