Canonical recently released Ubuntu 15.10, nicknamed Wily Werewolf. In the past, an autumn release of Ubuntu Linux like this would have been more experimental, warranting some caution when updating. Such releases weren’t quite update-at-your-own-risk rough, but they were often packed full of new features that were not fully baked. (For example, the now-shuttered Ubuntu One first debuted in 9.10. The Unity desktop became a default in 11.10, and the controversial Amazon search results in the Unity Dash made their debut in 12.10.) Especially compared to the spring .04 releases that tended to be stable (and every two years packaged as Long Term Support releases), autumn was Canonical’s time to experiment.
Unfortunately—or fortunately, depending on how you feel about desktop experiments—that’s not the case with Wily Werewolf.
There are new features worth updating for in this release, but, on the whole, this is Canonical refining what it has already created. The organization is essentially getting ready for the next LTS release (Ubuntu 16.04, due toward the end of April 2016), which will also likely be the last LTS release based on Unity 7.