This update contains improvements, bug fixes and security updates, including:
- Further improvements to Touch ID fingerprint recognition
- Fixes a bug that could impact keyboard responsiveness
- Fixes an issue when using Bluetooth keyboards with VoiceOver enabled
For information on the security content of this update, please visit this website:
This goes without saying but jailbreakers should stay away from the update button. There is no jailbreak for iOS 7.1, so updating to iOS 7.1+ will result in loosing the ability to jailbreak. Most probably a new jailbreak will be released a couple of months after iOS 8 will be released.
If you do want to update your iOS device, you can do it via OTA ( over the air ) or via iTunes.