A great multi-FX unit that is very flexible - it can do kick rumble, colour a synth voice with distortion, EQ, filter, compressor, delay and reverb, or function very well as a FX send from a mixer (and probably a million other uses - I've also been using it on vocals and guitar), but I've found it most useful as a DJ-style master FX unit.
My only critique is that you can't get a clean 'bypass' sound through it - the filter always colours the sound a little, so I've had to create a bypass loop with a switcher module to get a 'clean' sound when I don't want any of the FX applied. But otherwise this is a fantastic model that can perform so many different roles in a setup.