I don’t remember much about plex photos, but facial (and object) recognition, photo map, easy sharing through albums (without the other person needing an account), and being open source are some features I imagine plex photos does not have.
it seems barebones still, because it is a very young app, and the UI is not great, especially on mobile.
It is the best replacement for Google photos that I have seen though.
you posted this on a open source platform that someone bothered to create.