I had 1.1.4 & 1.1.5. I upgraded to 2.0 and don't see anything wroung with it. People say it's not stable but I haven't seen one problem on my two iPod touches. 2.0 is fast and error free for me. Only thing bad I can say bad for it is it's a pain in the but to use winpwn to jailbreak it. I haven't figerd it out yet.
But with all the apps I seen for 1.1.4 & 5. Are not worth keeping. Onlything I liked about jailbreak is theming the icons and the screen behind them. So far there is no word of a summerboard or custumize that work for 2.0.
And can't find anything that says there working on one.
Would be nice to see these programs become one program for 2.0. But all I can do is hope and wait and see what comes out next.
After upgrading I can't go back the old firmwares becuse of the nice new options 2.0 has. Like the built in screenshots that move to your photos, and the push email is nice.