Liked it, but too much slapstick.
I just watched Crank 1 & 2 back to back (first time I've seen either), and I just loved Crank 1. Crank 2, however, added way too much slapstick and satire.
I'm reminded of the difference between Rocky Horror Picture Show and its sequel, Shock Treatment. In Rocky Horror, the timely pauses that invite audience participation were entirely unplanned happenstance, whereas in Shock Treatment they tried to consciously add those moments (which was incredibly obvious, and the movie bombed).
With Crank 1, any humor we see is derived from the surreal characters and storyline clashing with the real world they're taking place in. It was bizarre, and somehow just worked. But with Crank 2, they consciously tried to make various moments funny, which took away the surreal aspect and made it into an unbalanced cross between an action flick and Keystone Kops, with impossible bits tossed-in to make it over-the-top.
I can see the good story in there (the portion that continues from the first movie), and enjoyed that part of it, but the forced humor and abrasive silliness that was added really brought it down a few notches for me.
I'd love to see a third movie, but only if it went back to the mood and style of the first film and only contained humor that happens naturally as an extension of the story playing out, not anything written specifically with the intention of being "funny."