9 Things to Do Before Installing iOS 9.2.1

Get Familiar with the Downgrade Process

Apple is still signing off on iOS 9.2 which means you can downgrade back to it if you don't like iOS 9.2.1's performance.

This option won't last forever (probably one to two weeks) so it would be wise to get familiar with the downgrade process right now so that you aren't feeling rushed or panicked. 

Remember, there's no way to downgrade to anything older than iOS 9.2 unless you jailbreak.