Maybe my experience is unique, but since “upgrading” to version 1.1.1 of the iPhone software, my device is barely usable. The iPod, Safari and Mail apps crash almost every time I use them, and many long-standing bugs and quirks still remain (an example). As far as I’m concerned, 1.1.1 is a disaster, and not worth the iTunes Store.
Update: After realizing my case was, in fact, unique, I followed suggestions to restore the iPhone. So far, so good. After 3 hours of use, none of the apps have crashed on me yet.
Update 2: While on vacation I’ve been using my iPhone very heavily, and since the restore it’s been more stable than ever. I guess 1.1.1 isn’t such a disaster after all.