Vista sounds like a real PITA. I think I'll wait on a new computer until Windows 7 comes out.
We first tested VISTA and it blew chunks as it was a tremendous resource hog. After Service Pack 1 it runs really, really quick and is VERY stable. We are now recommending people move towards it as new computers are purchased.
As far as a PITA, not really - it is keeping Joe User from messing things up. If you are a seasoned windows user, turn off these checks and balances built in (like UAC) and march forward.
Remember, Windows 7 public beta comes out in January or February, and the new O/S is scheduled for release later in '09 which means SP1 will follow first quarter of '10. Do you really think MS is going to release a perfect product first go around?
We are primarily a Windows shop and we always wait for the first Service Pack before we deploy to the masses.
Go with Vista if you are already a MS user, you will not be disappointed.