This thing is brilliant.
If you're familiar with Electro Harmonix products, then you'll know what to expect - superb build quality and creative functionality. This thing has both in spades, mine has survived beer spills and produced some truly wonderful sounds, live and in the studio.
There's no superfluous controls on here, so it's not needlessly overwhelming. Everything has a very clear function, and will have a massive effect of the sound.
To the sound itself, a massive range is possible. The blend control allows you to be sure that no low-end is sacrificied, which is usually the one main drawback of fuzz effects. I've found the pedal will do pretty much everything from a subtle, dirty overdrive, to a full on wall of stoner fuzz. Hours of fun to be had by slamming out chords.
Engaging the crossover control opens up what is effectively a second fuzz effect (2 in 1, how bad!) and you can adjust the high pass and low pass filters to your heart's content, for an altogether different kind of fuzz. I find this option tends to open up a range of more grinding tones, which wouldn't be out of place in hardcore, death metal, etc. I've used this in a few situations to produce screaming high gain feedback, and other noises. Really with this pedal, your imagination is the limit.
The -10dB switch is a life-safer, as the signal coming off my pedalboard is quite hot, especially when the Big Muff is thrown into the mix. The master volume knob has ample headroom to get you back where you need to be.
This has been well worth the money, and I'm not going to be looking for any other fuzz pedals any time soon, because it just does everything so well. I'd highly recommend testing it out for yourself.