Like all of MS's Operatings systems, definitely wait until at least Service Pack 2 is out.
I work for a big company and we're something like 2-3 years behind the 'most current' OS Microsoft has out. Sounds odd at first, you'd think a multibillion dollar a year company would be bleeding edge, but the truth is they'd rather play it safe and wait until all the kinks are ironed out... and that's usually sometime after SP2 comes out.
That's my personal recommendation for us consumers... wait for SP2. Sonnie and Mech I'd also check your free upgrade vouchers and make sure they don't expire. If they do, I'd say go ahead and get the disc and just shelve it until SP2.
Oh, not that this matters because I think everyone now has a DVD Rom in their computer, but you need a DVD drive to install Vista. The disc image is over 2Gigs in size!
In the past I usually had one system sitting here with the latest and greatest OS on it for testing purposes and so I could get used to the OS, but my wife decided to blow up her PC and the spares so no more test units for now
In March I will be building a HTPC from the ground up as an HTS project and I'll be installing Vista on that. Not because I am in love with it or anything like that, but to identify any problems that people may run into. Wish I had a free upgrade, that way I wouldn't have to shell out the bucks for it!