My sister in law just purchased the iPhone 3GS (don't ask) and I was wondering whether I should update the phone with iOS 5... I know about the battery issues. I am more concerned about the performance aspect. I do not know what version of iOS is loaded on her unit. Probably iOS 4.x... Speed and performance wise it seems to be doing great. I do not want that to be ruined after upgrading the device to iOS 5.