Serenity for Android is a Plex client for Android. It integrates with your Plex server but provides its own interface. This was developed originally for larger Android devices when most apps only looked good on phones.
The app works well on tablets and TVs, touting support for Android TV, Google TV, and Amazon Fire TV. After February of last year, development appeared to stop and the app did not see any more updates.
That has very recently changed. Two days ago the Serenity for Android account on Google+ posted news and a new version of the app. The app is returning to development and there seems to be some promising news.
This new version, 1.9.5, adds support for Marshmallow, supporting the new dynamic permissions system. It also updated the version of the Android Support Library, fixing bugs and performance issues related to those libraries. Google TV is still supported, so those users don’t need to worry about the app breaking.
The developer also discussed an upcoming milestone which will add universal transcoding. Some users have reported that their media, which have particular media codecs, did not play. With this transcoding change, it should be possible for any media file to play fine without needing to divert users to a third-party media player.
The app is available on Google Play, although the most recent version isn’t uploaded yet. You can alternatively sideload a trial version.