I've actually started using it for designing my next build, and it's really powerful: you basically edit the parameters of your design, upload svg of your shapes and it does the rest for you.
I have found several glitches (like selecting "neck through" as an option shunts the body all the way at the end of the board instead of the transition point you designate) but I think it's probably because on Windows it's not currently supported for FreeCad 0.19.x (but on 0.18.x I could not load SVG without errors so it's a step up).
Recommended to give it a try!
Here is something I am working on :) (multiscale 5 string bass)