I bought this pedal for the price, and I think for the price, it sounds pretty good. I liked it more than Digitech's and Boss's offerings to the bass distortion world, and its cheaper too. The overdrive mode is probably my favorite mode, it has a round, older-style distortion that I like, think more along the lines of old Geezer Butler and maybe Tim Commerford tones. At low drive settings, it can sound a little weak though. The distortion mode is also pretty good, with more of a modern hi-fi distortion sound, a little treblier than the od mode. This mode is a little stronger on low gain settings, oddly. The clean mode is just a transparent non-overdriven mode, useful if you want to use this pedal as an eq pedal or as a simple volume boost. This pedal really does preserve the low end pretty well, too well actually. With a bass-ier bass, such as a active humbucker equipped bass, it becomes really muddy-sounding. It's literally the only overdrive pedal I've had to turn the bass down on.
The attack switch is a unique feature, it adds quite a bit of treble and mids to the signal, making your bass sound a bit more along the lines of Justin Chancellor's tone. It also adds quite a bit of noise, though. Overall, I'm not really a fan, as it causes some odd treble distortion even on clean mode that really doesn't sound good to my ears, however with less trebly basses(I play a jazz bass), it can really liven up the tone, or put it more into the kind of noisy distortion that industrial music seems to love so much.
Overall, this pedal sounds pretty good, but it's far from the best. The gain range is pretty low; the overdrive doesn't go as clean as I would like it to, and it doesn't go as ridiculously overdriven as I would like either, it just kinda sits inbetween the two extremes. You can still get close to a good variety of tones, from the synth-ier tones of Christopher Wolstenholme to the more organic tones of Tim Commerford, but it won't quite reach them. Overall, a good value, but there are definitely much better pedals out there.