This thing's a beast, I use it mainly with my volca sample to add that analogue oomph that I felt the sample was missing.
It works as a kick obviously but it can also do massive sub-basslines, there are also some good videos of people using it to play melodies via MIDI [see Oscillator Sink].
Pros:
Massive sound.
Same form-factor as the other volcas.
Fun to mess around on!
Cons:
Some blips at the start of pattern-chained sequences.
Relatively low feature-to-cost ratio (touch FX are cool tho)
Conclusion:
It's probably my favorite volca, for some reason it's simplicity speaks to me.