I think, having now slept on it, the main difference between Dark Knight and DKR is, in Dark Knight, the story was pretty well self contained. You didn't miss much of anything if you had no knowledge of the comic history, and just knew what had happened in Batman Begins.
In DKR, I felt like I was able to enjoy it more than others might, because I knew the history. I went in already knowing about things that other people considered twists, primarily because I was aware of previous stories and characters.
Having said that, I really liked it, and will definitely watch it again in theaters. I did not feel it was bloated or overly long, like some have said. In fact, at the end, I was left wanting more.