BFD2 has a SLEW of cool new features, but here are the highlights for me:
*You can choose 3 different sizes of drumsets, meaning the number of kitpieces that are available as a single kit (the largest one is over 30!!!)
*Each instrument has this super-cool little drop-down menu that has several different "characters" of the sound...dry, roomy, dampened, etc. So you choose a snare drum, then you can choose if it's high and pingy like a piccolo, or fat and beefy, or room sound, etc. Especially cool for bass drums too!
*OK, here's the big one for me: DSP effects, EQ, and compression FOR EACH INSTRUMENT. Man, THAT is cool!
Plenty more to add, but that's the nutshell version, at least the stuff that I am impressed with.
And the interface is very cool too.