So far pretty good! I had a Chorus mechanical rim brake groupset that I wanted to use on a disc frame, so not many options were available (project thread soon). Setup was incredibly easy. Even easier than caliper rim brakes! In terms of power they are reasonable. More powerful than a rim brake, but less powerful than full hydraulic (bet you didn't see that one coming). They are better than other full mechanical disc brakes I have tried. They are very light too, if that matters to you.
If you already own a groupset that you want to convert to disc they are great. If I was speccing a bike from the ground up I would get full hydraulic. Better performance for the money.
Path Less Pedaled has only good things to say about them: https://youtu.be/N-cfoKRH_wU?t=218