XBMC 13.0 "Gotham" was probably the best release made by its developers and incorporated numerous features and some very cool options. The devs started working on an update for XBMC almost right away after the launch and, a Release Candidate later, the 13.1 version arrived.
The features that were introduced in the 13.0 update have remained in place. Users will still have access to Android Hardware Decoding (for 4.0 and up), Raspberry Pi and Android speed improvements, Stereoscopic 3D Rendering, better Touchscreen Support, better UPnP capabilities, numerous Audio Engine Improvements, and Settings Improvements. This is mostly a maintenance release.