I'm using this with - well - some guitars and - hm - some amps. It has a very cool, dirty personality. The fuzz is never noisy or buzzy. At least it isn't in mode "1". If you turn it into mode "2" you get crazy bass-and-treble insanity. Since mode "2" is less expressive than mode "1" I'm giving it an eight here.
What's fascinating about the standard fuzz is the dynamics. It has insanely natural sustain and it reacts beautifully to my playing. I can turn the guitar's volume down to almost zero and still get great sustaining fuzz sounds. The more I turn it up, the dirtier the sound gets.
As I mentioned "dirty" - you can't get a clean octave-up (let alone clean fuzz) from this one, but there's some amazing cross modulation that can turn chords into atonal trash and muted notes into ring-modulated sounds. And, because it's so sensible to the playing, this can be nicely modulated.
I must say that I have no other fuzz in my collection that's as expressive as the Standard Fuzz (currently consisting of several Vox Tone Benders, Fuzz Face, Kimbara Fuzz Tone, Kay Fuzz Tone, Maestro Fuzz Tones etc.).
One of the downsides is that it doesn't sound so well with amp distortion.
Now, sound quality for a fuzz, well...
If you like fuzz and would like to explore the world of dirty fuzzes, this one is killer. And they're still fairly cheap considering their dynamics and expressiveness.
So, to summarize:
Pro: Mode 1, dynamics, expressive, noise-free
Cons: Mode 2 is of questionable use, doesn't play well with amp distortion (but hey)