Firefox's stable release channel for Android has bumped up to version 36.0 after spending about a month in beta. The most notable change in this update is a completely revamped tablet interface, which better uses larger screens and makes the app look more like its desktop counterpart.
There is now a full-screen version of the tab switcher, which might make management of large numbers of pages easier. A developer of the new look says that this page will be receiving several new features in the future that utilize the empty space better.
For reference, here's a snap of how things looked on tablets before the update, in Firefox 35.0.1:
Note that all but the current tab were out of view if you didn't enter the (less obtrusive) tab switcher.
The other headlining change is added support for HTTP/2, the new protocol that just received approval by the IETF, making it the future standard for the entire web. This won't mean a lot to end users, especially at this stage, but it's a signal that Firefox has no plans to cease being a modern browser.
While not specific to v36, this update will not fix a new bug that prevents Chromecast tab mirroring from working properly. The ability to mirror tabs (a la Chrome) appeared in v34 and was working when v35 made the stable channel. According to Mozilla's bug tracker, the apparent cause of the lost functionality is an update to Chromecast, not Firefox. The device can no longer parse the video codec coming from Firefox, so you'll get nothing but a blank screen when you try to mirror. Users may be disappointed to see that no fix is present yet, and it looks like v38 is the target version for it.
There are many other under-the-hood tweaks in the update. For those, check out Mozilla's release notes.