I've been using it pretty much since it debuted, never had any big issues with it. I found Hotmail wouldn't let me read or delete mail for a couple weeks, but that magically cured itself and works fine now. I experienced some media trouble like Jay said too. So far, it's clean, easy to use, and I'm enjoying it much more over IE!
The bookmarks icon on the right side took me forever to get used to though.