
As mentioned before, iOS 10.2.1 is a minor update containing a series of bug fixes and stability improvements in the background. Since its developer release yesterday, folks who have updated to the new firmware have yet to find any outside changes.
Folks signed up with Apple's Beta Software Program can head over the Settings > General > Software Update to install iOS 10.2.1 beta 1. Of course, the device will need to have Apple's Beta Software Program configuration profile installed.