As a fan of the band Mudhoney, I was. at first. disappointed to find out that a pedal that shares their name was described as an overdrive. and not a fuzz pedal as the band was famous for using.
And in fact, with the boost disengaged, it's a serviceable OD/Distortion pedal. Crank the gain and you get a very nice valve-like distortion. But hit the boost and the pedal turns into a huge fuzzy distortion very reminiscent of its namesake. With the boost on and the gain backed off a bit you can get a great dirty boost that can really push a tube amp into distortion.
A lot of versatility in such a simple setup, I'd highly recommend it if you're looking for a pedal that can give you a nice all-purpose boost, a big grungy fuzz, and everything in between.