I saw it last night and I'll give it a C+.
I've never read the book, but this felt like a lazy adaptation of the much better novel. All the elements of a good film were there, but nothing was done with care or quality. The characters were underdeveloped, the writing was mediocre, and the action scenes were uninspired. It felt like the director was just going through a checklist of things taken from the novel rather than carefully crafting a quality movie. Fortunately, it was a very good checklist, so I did enjoy the movie. However, it should have been so much better than it was.