Having now seen the thing in flatscreen - without 3D, or the novelty of 48fps and IMAX - if I could lower my score on the poll I'd lower it to C-.
What the movie has going for it is beautiful scenery and the performances of some of the actors - Freeman, McKellan, Blanchett and Armitage chief among them. That said, it's overlong and overloud. The action is preposterous; by the third act everyone is Wile E. Coyote, repeatedly enduring impossible falls and violence while not appearing to suffer so much as a broken finger. That makes it hard to maintain much interest in the action.
Worst of all, the tone and hence the charm of the novel is mostly absent. They might as well bring in giant robots.