O'k, this is my second replacement. It seems to be fine but! The jerky animation in folders and sometimes in games is bothering me! I was using the 3 GS for more than a year and spent some time with it running iOS 4 and it surely was jerky on iOS 4 at times but not that often. In general it's running smoothly, but in some games, especially racing games, it freezes for a second or so like it's loading something from the buffer. Sometimes it seems to suffer from lower FPS too. My first iPhone 4 had a very bad reception, another one had two yellow spots on the screen, I was using them just for a couple of days and now cannot easily say if they were acting the very same way as my current one does. I restored it for a couple of times (form a back up and as a new one), but it didn't change a thing. I'm not happy about swapping it as I feel like I'll end up with another defective phone but with a different problem (oh man, it was so easy with the 3GS last year) But if it's a real issue that concerns only my device, I'll give it a try. Is anyone experiencing the same things?