Tried with Suffusion (the most used professional free one) and will mess the css on the frontend. Tabbed widgets will appear overlapped and the a webel is overlapping only half on the div it self for all elements in frontend.
This means that you see double the same element for almost anything on the page.
Lack of support for major issues like this is just enough to give it 1 star.
It might work for some, but on what themes? And not on Suffusion???
I can change my review if I can make it work with css, but it would be a long and painful hassle. I'm also fairly convinced it has issues with ssl pages, so my css is always embedded in the html source, this does not make it easy to debug.
It also interferes with the front end BuddyPress Docs plugin causing any front end edit doc page to not display the tinyMCE, so no visual on that either. (I guess it can be workaround it by going into php code and disable it for all doc pages - since those have already front end editing.... - but the hassle - and again no support)