I'm using this primarily with my bass and it really provides a really nice and thick fuzz that really sounds consistent from the lows to the highs on a bass.
I also sometimes use it dialed back for some guitar parts and such. And even some synth sometimes but that's just me being nutty.
Really nothing major to complain about. Knobs feel a bit insignificant and light. They are not loose, they don't wiggle or anything. The plastic knob feels hollow and cheap-ish though. But knobs are knobs. Switch 'em out if needed. :)
Other than that the build-quality is really robust and weighty.
Sounds great, feels great. It's just great! :)