I couldn't handle how slow iOS 5 GM made my 3GS run. I know it's an outdated model but if anyone feels the same and would like to downgrade here is a good guide to downgrade from 5.0 to 4.3.5/4.3.3 and here is another to downgrade to iOS 4.1 if you have your SHSH saved. Hope this helps some of you who don't like the lag!