I used Vista for a month or so after it came out, but I felt that the bugs and driver issues forced me to revert to XP until Vista SP1 came out.
SP1 fixed the majority of the issues I was having, and manufacturers had finally come out with halfway decent drives by then, so I re-upgraded to Vista SP1 and have been using it on 2 of my 3 machines since then.
Vista has its pros and cons (with the pros being mostly aesthetic), but I'll be quite glad to upgrade to 7 once it's released. I'm consistently hearing good things about its performance and stability, Vista's main cons.
I'll almost certainly end up having to upgrade my work to Windows 7 in the next couple of years (70 desktops and 15 laptops), but I'm riding XP for as long as I can, for sanity's sake.
