iOS 5.1.1 update.
This update has made the already full of bugs and loaded with issues iOS 5 even worse. Now my New iPad keeps crashing, leaving an outline of the app folder on the home screen. I've had to restart twice in two days to fix this. As well as this the iPad and my 4S keep losing Wi-fi connection. Other devices don't so it's not the network. I'm not at all impressed with iOS 5.0, 5.0.1, 5.1 or now 5.1.1. All have been by far the least stable yet most buggy and problematic. Really unimpressive considering the amount of time it took to get it to public release as well as a record number of beta releases. It just doesn't work.
iPad Wi-Fi + 4G, iOS 5.1.1