Apple has released to fix various bugs and address an issue that could cause ringtones purchased from the iTunes Store to disappear. In terms of security updates,  that wasn’t already included in iOS 8.1.1.
Since Apple didn’t see fit to describe any other bug fixes or include any security fixes, if you don’t use purchased ringtones, we can’t see any urgency in installing this update. That said, we haven’t seen any widespread reports of problems, so it’s probably innocuous. Be sure to back up your device before updating.
If your purchased ringtones have gone missing, update to iOS 8.1.2, and then visit Apple’s page on that device to get them back. Apple describes the process in a .
iOS 8.1.2 can be obtained on your device via Settings > General > Software Update or on your computer in iTunes. It weighs in at about 28.2 MB on the iPhone 6, though the size will vary depending on your device.