Not my favorite guitar fuzz/distortion pedal, but obviously still popular and liked from others.
Good, if not meanwhile legendary vintage Fuzz/Distortion/Sustain pedal with a nicely unique sound, which you can like or also not, the highlight of the pedal certainly is the combined high pass / low pass tone control, called Filter here, which allows a good - or even better, compared with other units from the same time - adjustment to the used guitar and amp.
Nembrini typical very good, authentic and convincing sound, the -15dB option is a nice addition for some cleaner tones.
A Nembrini version of a Small Stone, Small Clone, but also maybe of a Pitch Fork would more be my taste, but this plugin is freeware and (not only) for a freeware the sound and programming quality is excellent.
By the way, this unit also sounds fantastic in front of eg. a Taurus, Minimoog, OBX or other (vintage) synthesizers, but also in front of a Hammond! In front of them I like it even more than as a guitar pedal.