As a disclaimer, I am not a Big Muff connoisseur. I've never owned one before this. I also tend not to like fuzz as an effect. I'd characterize this box as a cross between distortion and fuzz, maintaining enough definition for chord work. If you're reading the reviews, you've probably already done your research on the features, but I'll cover them anyway.
Three simple controls, Volume - Tone - Sustain, with the Sustain control being more or less a Gain control. The enclosure is a smaller, pedalboard-friendly size. The pedal incorporates two of the (supposedly) most popular Big Muff mods with switches, Tone and Wicker. When Tone is switched off, the Tone control and its tone-shaping circuitry are completely disconnected. In this mode, the distortion applies to the entire tonal spectrum evenly, and it also produces a significant volume boost. The Tone knob does nothing.
When Wicker is switched on, it removes three high-frequency rolloff filters that were added to the original Big Muff circuit to smooth out the sound. Disconnecting these makes the sound a bit raspier and rougher, with a high-end frequency boost.
I use this pedal running into a mild overdrive, the Catalinbread Dirty Little Secret, which "conditions" the signal. I play with the Tone off and Wicker on, and even with the Volume and Sustain controls set fairly low, this combination results in a wonderfully thick, massive distorted tone that is still pretty smooth.
If you're looking to get a Big Muff, and you're not a snob about which version, the switchable mods on this one are really great for experimenting to find your own sound. Not to mention that, at this price point, it will be much cheaper than some vintage Muffs. Highly recommended.