I used to have a Boss MT-2 Metal Zone pedal. I loved the sound, but it was hard to find good settings. If one of the knobs was turned slightly it sounded quite bad.
That's not the case with the Metal Muff. The knobs can be in almost any position and it still sounds good or OK. I would say that it is a good metal pedal, in fact the best I've tried so far, but I'm sure there are better ones.
Something that I find lacking in many distortion pedals is that the sound when playing palm muted is very thin. That's something that the Metal Muff is good at.
I didn't find the top boost function useful at all. It makes it sound shrill. I can recommend this pedal!