I was hoping that the 3.1.2 update would resolved the issues that made my iPod touch g2 unusable (random freezes, slow response, crashing, etc.) but unfortunately, it completely hosed my iPod. It seemed to have gotten into some kind of restart loop—Apple logo, spinning thing, restart, Apple logo, spinning thing, restart, etc. After waiting an hour for it to finish I gave up and reinstalled firmware 3.0.

I usually have no problems with Apple updates in general (MBP, MacPro) but firmware versions 3.1, 3.1.1, and 3.1.2 have been disasters...