Actually very faithful, and very good - just rock solid across the board, and brings the book to life in suitable style. The moral lines and complexities of Moore's text aren't sacrificed, and the different ethoses represented by Rorschach, the Comedian, Ozymandias, Dr Manhattan, etc come through clearly, while the action scenes are exciting and emphatic; the mood is about right too, if not quite as despairingly heavy and grimy as on the page. And the actors do enough to convince; Patrick Wilson as Dreiburg and Jackie Earle Haley as Rorschach are particularly good. The soundtrack is interesting, too, leaning heavily on music from the 60s (and 70s?) despite the alternate-80s period setting.
(w/ M)