iOS 9.2.1 brings several bug fixes, security updates and feature improvements to apps like Apple Music, News, Mail, iBooks, and more. Apple added that an "issue that can prevent a completion of app installation when using an MDM server" has been resolved.
[FONT=Helvetica Neue, Arial, Helvetica, sans-serif]Folks with compatible iPhone, iPod Touch and iPad models can download the new software directly by going into Settings > General > Software Update. While this is a minor update from Apple, it's always good to be current if you're not planning to Jailbreak. [/FONT]