As you may know, Canonical is constantly upgrading Ubuntu Touch, the mobile version of Ubuntu.
According to Canonical’s Łukasz Zemczak, the Ubuntu developers have managed to implement Mir 0.18, a new UI Toolkit and updated versions of the Web Browser, Address Book, QtPim and Buteo. The new Web Browser app was added only on the channel based on Ubuntu 15.10, because the Ubuntu 16.04 one has some Oxide-Qt video player that does not permit the browser to get built on it.
The biggest update is Mir, the display server bringing a huge list of fixes and new features.
As a reminder, Ubuntu Touch comes pre-installed on Bq Aquaris E5, Bq Aquaris E4.5 and Meizu MX4, but is also officially supported on Nexus 4 and Nexus 7. While still young, Canonical is constantly working at it and releases a new update every 6 weeks.