I think I know what the OP did. I did the same thing.
When you upgrade the OS, the apps take a long time to synch and transfer all the settings. The lock screen no longer shows a message that says its synching. There is now a small spinning wheel in the status bar. It may appear that your phone is finished, but it is still transferring all the apps.
The iTunes window will show apps synching. But if you just look at the phone it is very easy to assume that your phone is finished when in fact it is not. I made this same mistake and my apps would not open. They would flash for a sec and go back to the home screen.
iOS 5 has been great for me ( once I synced all my apps properly). It's fast, reliable and battery life even seems to be a bit better (was jail broken before)