The movie's most glaring flaw is that the brothers and their screenwriters, Terry Hayes and Rafael Yglesias, don't manage to preserve the secret of the Ripper's identity for nearly as long as they intend to.
It's good enough, smart enough, and people will like it. It's also a high-concept cop-out, a convention-strangled genre movie that never zigs when your every instinct is screaming that it's about to zag.
The flat, gross-out live-action bits, directed by (surprise!) Peter and Bobby Farrelly, don't jive with the zippy, Tex Avery-style animated segments, directed by former storyboard artists Piet Kroon and Tom Sito.