Electro Harmonix have a lot of cool pedals and some of them are really weird. This one is just a straightforward overdrive pedal with separate treble and bass knobs. The marketing is full of buzz words: it's supposed to be a "full range" overdrive and words like "smooth" are used to describe it.
I find the pedal to be nothing spesial and definitely not "smooth". I might agree with "full range" if that means it delivers all the nasty high frequencies you would normally want to filter out of a distorted guitar sound. Basically it's just a boring and slightly harsh sounding overdrive. If I had to compare to a more widely known pedal I would say it sounds like a more harsh sounding OCD. The harshness can be reduced using the tone controls but unfortunately the tone controls aren't very good. Unless used very sparingly they sound really bad. Raising the treble is not a good idea as it sounds really harsh. IT seems to boost frequencies far above what is normally considered "nice" for distorted guitar. But lowering the treble doesn't work either as is sounds dull and uninspiring really fast. The high control seems to have a much too wide range, destroying the upper midrange when lowering it and boosting too high frequencies when boosting. Same with the bass knob, raising it makes everything muddy. It seems to somehow work with the wrong frequencies. Lowering the bass knob makes everything too thin. It seems to raise/reduce the entire lower midrange AND the bass range, far too wide a range to be useful.
The gain knob also has a pretty wide range, which could have been cool. Unfortunately it doesn't sound nice in the lower "edge of breakup" settings. It's just to hard/metallic sounding for that. And after 12 o'clock there's not a lot of difference, it basically sounds the same from around 12 o'clock and upwards.
I guess this pedal sounds okay with higher gain settings if you need that full chord hammering "wall of sound" type of overdrive but that's just about the only thing this pedal sounds ok for. And there are other pedals that do this better.
Also, it doesn't play nicely with other pedals. Stuff that would normally work with similar sounding pedals, like running a TS-style pedal into it, just sounds... bad.
It's ok for the price I guess but there are LOTS of better overdrive pedals out there, even in a similar price range and also within EHXs own range. I generally like EHX overdrive/fuzz pedals but sadly not this one.
Build quality... well it SEEMS ok but it's EHX so basically you can expect it to break down at any time. Or it might work flawlessly for years. You never know with EHX.
Not recommended. At least try before buying.