This pedal (for those who do not know) was the basis for a company in the US buying a job lot, painting over the casing, changing some components totalling about £2.00 and 30 mins work tops, and charging about £150 for a 'boutique' pedal. the result caused uproar in the Boutique FX market to the point of forum bans etc. The changes they made however made sense and are worth carrying out (which will be explained later on).
The pedal itself is based on the Fulltone OCD pedal which is one of the better pedals on the market right now. I've never played an OCD so don't know how it sounds, however what I can compare it to is a Tubescreamer type of pedal. That's more appropriate as you would probably be buying this pedal as your main OD or main boost pedal and would have to make a decision against the TS pedals out there.
The pots are touchy and it is tough to dial into the sweet spot on the pedal quickly. The 'track' of the pots are not too great either but is helped with resistor changes to each pot as per the 'Alpha Mods'. There is a High Pass/Low Pass switch that does what you expect. The gain pot does nothing past 12 o'clock, however there is so much gain in this pedal that you generally won't need to head that far up. The tone is very wide and this means it is easy to match it to your overall amp tone, or just create a whole new sound. There is also a lot of volume which pleased me as I would rather have too much volume than not enough.
Compared to a standard TS pedal (such as the Vintage Overdrive) there is less mids (almost scooped), lots more volume and lots more gain. I would recommend this pedal wholeheartedly even if you own more expensive equipment. This currently stays on my board alongside a Jekyll and Hyde V2 as my 'hard rock' sound for when I need extra grunt and it does the job admirably.
If you only buy one pedal regardless of how much money you have then buy this. It fooled an entire boutique effects community, and those of us that have already bought this pedal know exactly why!
NOTE : there have been tons of words written about modding this pedal. It sounds great out of the box, but found that making the 'Alpha Mods' changes made this pedal even better. The only difference is by soldering a 10k resistor across the Tone knob rather than the suggested resistor you keep the tone pot in check without introducing an analog blanket.