If you work in IT, you'll want to think about installing the iOS 9.2.1 beta ahead of the public release date.
Installing the iOS 9.2.1 beta early will grant you the ability to test systems/services and apps ahead of the iOS 9.2.1 release date.
As we've noted many times, Enterprise problems are some of the most common iOS problems. Testing the update ahead of time could help you diagnose issues ahead of time and hopefully fix them before they become a huge problem for you and your clients.
IT professionals who support end users at a company will probably want to try the iOS 9.2 beta.1 to prepare for potential support calls and trouble tickets.
iOS 9.2.1 isn't a huge update (at least not yet) but it has the potential to cause you headaches. Trying it ahead of time could cut those headaches down or eliminate them completely.