Initial release January 12th. Three hotfixes released, latest on January 28th.
Read the release notes and additional information available on the Nvidia Forum. If there is no compelling reason to install Shield Experience 9, then do not do so.
Basically, if it ain’t broke, don’t fix it.
I’ve a Shield 2015 Pro with Shield Experience 9.0 and 3rd hotfix.
It works fine as a Plex client playing movies/shows from my Plex Server on a Synology NAS.
I do not use the Plex server on the Shield. From what I have read on other threads, the Nvidia hotfixes and a Plex Media Server beta release are both required for PMS to work on a Shield with Shield Experience 9.0.
Before installing Shield Experience 9.0, you should review the information on Nvidia’s forums, as other apps & features are also having issues.
Thread discussing Plex Media Server issues with Shield Experience 9.0:
Nvidia Shield Forums:
https://www.nvidia.com/en-us/geforce/forums/shield-tv/9/