With version 2.1 I think they nailed it. Personally, I would love more Apps like this; a nice GUI that is intelligently organized, with the command line tools available for when you need them.
There is some validity to the claims that typing in a file path is not very GUI-like. It would be good to see drag-and-drop implemented there.
Instructions would be my next priority too, but even as it is now, I prefer this over all the other options I have tried. I had my backup done and boot-able within a few minutes of downloading the application.
This has become my new favorite Mac OSX application!