Version 5.1.1 of iOS addresses AirPlay playback problems, fixes a fickle HDR photo option when activating the camera app from the iPhone and iPod touch lock screen, makes syncing bookmarks and reading lists from mobile Safari more reliable, and takes care of problems some iPad users were having switching from 2G to 3G networks. It also banishes a rare error message that could crop up after making purchases from the App Store.
If you're already using iOS 5, which came pre-loaded on the iPhone 4S and the new iPad, it's possible to update to the latest version without connecting your phone, tablet or iPod to your computer. That's thanks to iOS 5's new over-the-air update feature. Still, it's recommended that you plug your device into a charger to prevent its battery from dying mid-update.