I just received mine today and I've just spent about an hour mucking about with it and comparing it to the Whammy 4 (which I use loads).
On a first impression the settings that I'm having most fun with are 5th ^ / Oct ^, the 5th ^ on it's own and the Oct ^ / 2 Oct ^, all of which are settings that aren't on the Whammy 4. The tonal difference between the Whammy 4 and Bass Whammy is huge, I was getting annoyed with how much a tone sucker the Whammy 4 was. Overall I'd say the Bass Whammy sounds a lot smoother. I'm not taken aback by the Chord setting, that's doing funky stuff to my tone, it sounds very digital as someone else mentioned before.
At my next rehearsal I'm gonna give it a go, and also keep the Whammy 4 on my board to compare.