Egmde is a "worked example" of using Mir written to accompany a set of blog posts. It is a basic, usable graphical shell, not a not a fully functional desktop environment.
These blog posts are listed here: https://github.com/AlanGriffiths/egmde/wiki
They don’t cover aspects of a desktop environment that are not related to using Mir. Missing functionality includes: integrating into the system for screen locking & suspend, policy kit integration, internationalization, etc.
To use egmde as your desktop, select it when logging in, to run it on your desktop run "egmde".
There's more about customizing the appearance of egmde on the Ubuntu discourse:
There is also some limited support for "remote desktop" meaning egmde can be used over
ssh's "X forwarding":
$ ssh -XC <user@host> sh -lc egmde