it works really well with bass on some modes but not so well on others.
The harmony setting is ok, but due to the low frequencies, it seems to struggle tracking wise.
The pitchshifter set for a chorussy type thing sounds great, although perhaps a little digital - might be what you're looking for! It also has a wet/dry blend on the pitch shift mode, so that opens some possibilities too
Where it shines for me is with the s bend mode. 3 octaves down and 4 up available. variable rise and fall time from almost instant jump to a slow sweep. The pedal can be totally self contained - ie you won't need an external exp pedal for the sweep, as the switch is momenary in this mode, and will hold the note you're set to reach until you release it and the pitch will return to normal according to the fall time.
It sits really well in a dense band mix, and is really fun.
in short, get yourself to your local boss dealer and give it a good try!
If you're near London try Stompbox / Effectspowersupplies - really great guys with excellent pricing and a great range of pedals in stock! \ad (!)