I've been using OS X Jaguar since December 2003 and so far my experience has been quite positive. It's never crashed yet and there's only been a few times when the Finder has stopped responding. The one thing that has marred my experience has been the Help Viewer.

The default text in the Help Viewer is painfully small on my system (17" iMac) and so I increased the text size. Little did I know that changing the text size would prevent the links in the TOC pane from working. It took me ages to find that out (months actually). Eventually, I found the answer on Apple's support site. So I reset the text size and bingo, the links work again. The text is painfully small again mind you, which is a bitch when you're trying to figure out how things work. I'm not the only one to have issues with the Help Viewer either. It's nice to know you're not alone.

Oddly enough, John Gruber hasn't mentioned it on his site, but I'm sure he's well aware of the text size issue (and maybe others too). He provides the best commentary and criticism about all things Mac that I've read.

Oh, and I still use Windows and I know all to well the pain of installing XP-- perhaps not to the extent as Mr. Pilgrim, but close enough. You should read the comments about his post too, they're just as entertaining (Warning: there's a lot of them, well over a hundred).