When I went from 3.x to 4.0 my phone slowed down, locked up, and I didn't like it. When I went to 4.1 all problems solved.
I've just been given my Uncles iPhone 3G, and it's currently at version 3.1 of the iPhone's firmware
I've heard some people have had problems with the upgrade to iOS 4 with the iPhone 3G, so I thought I'd be best to ask here:
1) Should I upgrade my iPhone 3G to 4.1 from 3.1?
2) Is 4.1 jail breakable yet?
Many thanks - Jack