There are only three knobs on this guy. One is for gain, which is normal. The other two are different than most pedals, they are named Bias and Volt. The manipulation of these sounds is usually only possible by opening the circuit board of the pedal. The Bias knob changes the signal flow up and down, which affects the sound in a way that is difficult to describe, but is very cool. The volt knob, as you probably can guess, adjusts the voltage which gives the sound a really gritty, really decayed sound. If these are the sounds you're looking for, you'll have no trouble using this guy.
The sound quality of this pedal is great, but only for people with a real interest in these very particular sounds. I've managed to get some really grainy, decayed sounds that really rock but are totally murky and thick. A good example of a song that features similar tones would be "Everyone Choose Sides" by The Wrens, for anyone who may be familiar with them. Other sounds on the complete opposite end of the spectrum include a great 60's style light fuzz that can be achieved by increasing the voltage and lowering the bias. This tone is great for adding a little grit to an otherwise clean sound, a little bit dirtier than what can usually be done with a Fender Twin when you crank the pre-amp. Overall, the sounds possible with this pedal are very particular, but can be used effectively in the right context. Also, I've used it nicely with my Strat/Twin setup, but I've seen it used with Les Pauls and it arguably sounds even better, especially with a good tube amp.
I like the uniqueness of this pedal, it definitely will help add a rough lo-fi sound to whatever you're playing. For this reason, I would have to recommend it for studio use over playing live. It might not be powerful enough to rock a venue (at least it wasn't enough for me), but it's properties will give your records a raw, gritty feeling that is hard to find in some of the more popular pedals. I have tried many distortion pedals but none really compare to this, except for those that have been doctored for the same effect. I'd recommend it to creative and experimental guitar players who care more about overall texture than purity of tone.