I've got the 32-bit version running OK on what is now a triple-boot/dual-HDD Pentium 4 - XP-home/VistaBusiness32/8x32.
It's very strange and the new "Start" tiled layout looks very much like a bolt-on.
Even stranger I haven't found any way to "properly" configure the Start icons. All I can do is move them around and switch between small (1 tile) and large (2-tile) sizes. Can't even find out how to add programs to the existing very eclectic collection.
And the horizontal scrolling is right royal PITA if (like me) you don't have a touch screen.
If you go to the old-style desktop there's almost nothing there, not even a Programs group on the Start menu (if you can make it appear - it randomly takes you back to the Start tiles following some logic I haven't yet fathomed!)
Now going to try the 64-bit version on what will be a triple-boot/triple-HDD system - XP-home/Vista64Ultimate/8x64.
OK, I accept it's pre-Beta so there will be a lot of holes, but parts of it seem fairly complete.
Definitely smells of Windows 7 with a quick makeover though.