It was very good; I highly recommend it. :) Particularly if you'd enjoy a gender-reversed version of The African Queen starring CGI rats, which I certainly always would. ;) I would have preferred claymation to CGI (really ... I'm just tired of CGI), but on the other hand trying to do most of the effects in this movie with claymation would have been a nightmare.
High points include Sir Ian McKellan as the villain, a Marcel Marceau frog with a cellphone over his face (believe me, it makes more sense in context), and the "We surrender!" joke. The only real low point was the junk they showed in the previews -- does the world need another CGI movie starring penguins? Now they're surfing, randomly. Although Charlotte's Web looks like it might be good to catch on Netflix.
There were lots of Wallace and Gromit in-jokes, of course, and a handful of Wolverine gags; but mostly it's designed to stand on its own, and it does. :) We enjoyed it.