From the user "Antibody" (known for his duel commentary videos) comes this nice video overview of the new features:
(please note that due to video capture performance reasons the graphic settings are pretty low, and the game can look much nicer with different settings)
On the longer term horizon of Xonotic development, there is the very exiting news that they are currently porting their game to run on the same engine that Unvanquished uses. With this the future of Xonotic is indeed much brighter, as their current engine has not seem much development lately. See more details in this thread.
Oh and while we are talking about FOSS arena FPS: A short while ago Red Eclipse also released a new version. Changes include updated to the AI Bots and a build in universal updater to easily follow the latest releases.