Once again, Federico's got us covered. Apple Pay (US only), Camera Roll, iCloud Photo Library, SMS Relay, and more.
Don't worry, this one is safe. If you're still wary of updating to any version of iOS 8 because of what happened with iOS 8.0.1, don't be. 8.0.2 was fine and so is 8.1. Go for it.
But, if your issue is storage space, then don't forget that you can update by plugging your phone into iTunes on your computer and you won't need that almost 5 GB of free space that you need for the OTA update.