We go through this every year, so apologies for not posting it sooner, but once again we'd like to remind everyone not to leave bad app reviews based on crashes or other "bugs" under iOS 5. Why?
Because iOS 5 is in beta. You're not supposed to be using it for anything other than testing your apps. Developers can't even upload iOS 5-compatible binaries to Apple right now, so there's nothing they can do about it, nor is there anything they should have to do about it.