It's a pretty great pedal for guitar, for bass (which it says its intended for) I wasn't impressed.
It's not like an octaver, it doesn't add super fat lows. It's almost like an attack re-distributor, changing your more dominant frequencies to lower ones. It's not an extreme effect; in fact, the only extreme you can go to is something that sounds like 0% bass which isn't the purpose anyway. It would certainly thicken up a guitar, especially single notes on the low E string. But for bass I didn't think it was that useful.