Summary: the document is written by a former regular committer to the gedit codebase.

It mentions a few concerns about recent changes to the software and the process surrounding it ('undo' and other frequently-used items of functionality are no longer immediately visible and accessible, scrollbar behaviour has changed, and the author believes that design changes have been made largely for the sake of changing the look-and-feel of the software).

There's a mirror of the gedit codebase on GitHub here: https://github.com/GNOME/gedit/

The addition (and subsequent removal) of the "tepl" text editing library and "amtk" internationalization may also be a point of contention: https://github.com/GNOME/gedit/commit/fa587e033c97fac65dacdb...