This is a very, very good movie, with excellently developed characters, particularly Aaron Eckhart as Harvey Dent and Gary Oldman as Jim Gordon. Some of the action scenes are hard to follow, but in the aftermath of those scenes, the viewer is able to figure out who won and who lost.
This movie is, as the title says, extremely dark. The overall atmosphere and the theme running through the movie are so dark and grim that they're almost oppressive.
Again, let me say: this is definitely a GOOD movie. It's just not a feel-good movie.