Bought tickets on a whim to see The Dark Knight yesterday evening; wow!
First, I would definitely recommend seeing this flick on IMAX/Ultrascreen...the large format makes the movie that much more immersive.
Second, I was very impressed with the story. A few words I would use to describe the movie: dark, fast-paced, humorous, witty, sad, surprising and action-packed!
Third, I can't imagine a better (or more totally different) role for Heath Ledger to "go out on" after his untimely death. No typecasting of him here...more often than not it was hard to remember who was playing "The Joker."
Fourth, three cheers for Maggie Gyllenhaal...she is SUCH a better actress and better fit for this series than the vapid Katie Holmes.
Fifth, just go see the movie. If you didn't like Batman Begins you probably won't like this one, but the story is so well put together and moves along so well you should see it anyway.