This 6-months feedback on its usage is a very important point. A related point about user testing was raised in the other thread about the potential Darktable rebrand. The video linked to in that thread talks about the value of “new user testing”, which is basically putting the software in front of a new user and asking them to complete a task. The ease/difficulty in which they do it will give an idea of how well the UX has been designed.
So far, the feedback on the module has just been from the enthusiastic users active in this thread, and they tend to be technical and proficient users of Darktable. Getting more feedback from a wider panel of users and on a wider range of pictures will be invaluable, although I realize that it might cause additional pain for @kofa!