Surprisingly painless installation process.
So far so good - no driver issues or anything, though I am running on a box with completely new hardware, except for an old hat dvd+rw drive. Took me awhile to figure out how to get Aero to actually work (the default theme is Vista Basic instead of Vista Aero, I later realized).
(and no, I did not buy it at retail price... picked up a copy for $50 from a friend who works for msft

)