This is a fairly minor update in that aside from compatibility with the latest patch, it's mostly just bug fixes. You can read more about that in the change log.
That being said, if you're outside the NA region I will caution you to not use this version until your client has 9.0.1. While RealUI itself could run on both, there may be some included addons or libraries that don't.
Additionally, MSBT has yet to be updated so I am making an early preview of the WIP RealUI_CombatText addon. This has very few options at the moment, but if you would like to try it out any feedback would be appreciated. (preferably on our Discord)