One of the most useful elements of Apple's new iOS 5 is the Reminder app. However, within minutes of getting my 3GS updated and logging into iCloud I realised my Reminders app was useless. This isn't a judgment on the app it's because I couldn't create an item let alone actually be reminded of anything. Only the Completed list displayed and there was no little +.
If anyone else finds themselves in this position the fix is rather easy but strange. Navigate to iCloud under settings. If Reminder sync is off turn it on. Let it Sync up then head back to the Reminders app and everything should be ready to go. Strange bug but certainly a bug.