Pretty much everything covered here
and most of those still happen with the latest release. The beta did ship with an older version...so I can't say if all their issues were related to that version of the editor.
Like you can somehow have a <h3> that gets a <p> embedded in it (still), then you cant get out so the entire content is being wrapped in the h3...so the only way to fix is dump back to html mode...but UserX wouldnt be able to understand how to do that.
The exact feedback was
"hyperlinks not working, buggy windows popping up, formatting is not intuitive - a little crude, clunky, and not that intuitive."
So most of that is due to beta obviously (like links not working), but in my previous talks with them the RadEditor was a big issue...not WYSIWYG, more like WhatYouWantHasBeenGimpedByTheEditor (WYWHBGBTE).