This is one of the hardest movies for me to write about in recent memory.
For the sake of posterity, let me say up front that I enjoy Christopher Nolan's Batman films a hell of a lot. Batman Begins was incredibly impressive, but its successor just knocked my socks off. I LOVE The Dark Knight. It was far and away my favorite movie of 2008, I was every bit as upset as everyone else when it was snubbed at the Oscars, and I maintain to this day that it is - more than any other - the movie that gave a certain amount of legitimacy to the comic book genre (though Whedon's Avengers has now legitimized it as MULTIPLE genres). It made for interesting and stimulating discussion, made a conscious choice to shake things up and not just play by comic book "rules" and explores some really interesting material. All in addition to being an enjoyable movie.
Which is why it really bums me out that The Dark Knight Rises is ONLY a pretty enjoyable movie.