I thought this movie was really well done. Usually super-hero movies don't stand out as pieces of film, but just within their own genre (not unlike comedies). I think Iron Man is a good recent example of this--Iron Man was a very entertaining film, and very good inside of it's own genre, but it still followed the same basic path that almost all of its predecessors took.
These new Batmen movies, though, can be compared to other well made movies on more than one level. The plot of The Dark Knight stands out as intricate and dynamic; the acting was masterful from both the antagonist and protagonist, as well as most the more minor players; the directing was also very well done, often giving the appearance of violence without actually showing violence/gore on screen.
Unlike most super hero movies, which have appeal as "summer movies", which are notoriously made for profit--to be big smashes but not timeless films, I thought this movie showed an appeal as a piece of art as well as a piece of entertainment. I guess the question here is how many more solid films can we expect out of this series before they drop the ball for profit?