If your 3g signal is weak the 3.1 makes it better, it has on my case. I also got better battery life and a better experience with the keyboard, no lag, works smooth. I have not had ANY problems with 3.1, I love it! Just make sure if you do update after it's done do it AGAIN and you won't have the issues SOME people are having.
I say SOME because those that upgrade and everything went smoothly the hardly ever come here and say how good it is. Only those with issues come and post problems. So don't make up your mind on those threads only. I never do and every update has been great for me. Just have to install the updYe twice. Helps every time!