I've been using Vista for about a month, and I want to kill it with an axe.
My primary complaint so far (other than the memory hog issue) is that it downloads upgrades that I didn't ask for, and since it needs to shut down and restart to install these downloads, it automatically shuts itself down without saving anything on the desktop. Not, "these upgrades will be installed the next time you restart". But rather "Hope you weren't in the middle of anything b*tch, like giving a crucial power-point presentation at med school, because your computer has decided that these upgrades can't wait another four f**king minutes, and it's going to shut down NOW."