With spoilers for TDK and Iron Man.

My dislike for The Dark Knight mostly highlights how good a movie it was.

For example, I find it interesting to contrast my enjoyment of Iron Man with the depressing experience of watching TDK. In Iron Man, the bad guy is not acted particularly well, and his evil is very abstract - selling weapons to terrorists. It's enough to cheer for the hero beating him, but not enough that the evil was palpable and disturbing. Compared to Heath Ledger's Joker, Iron Man's bad guy seems cheesy and boring. (Also, compared to Batman, Iron Man's hero seems to have it pretty easy). But that made Iron Man a lot more fun for me.

More generally, I didn't like TDK because I was gripped and drawn into a world that I found unpleasant. I am someone who, in general, often doesn't get drawn into movies because I am easily jarred by bad acting, writing, plot holes, etc. So the fact that I was so engaged is a testament to the effectiveness of the movie. (I was knocked out several times, but always brought back in. The first was the scene where Wayne wants to give up on Batman and get back together with Rachel. Totally cheesy.)

This movie was powerful enough that it makes me wonder if I should devalue previous movies - at least, movies that intended to depict evil. To be more specific: as a family man, when I see someone's family threatened, either:

a) I don't believe anything bad will happen, I trust the world of the movie to be safe and happy. So the threat falls flat.
b) I don't care about the people in the world. So the threat falls flat.
c) I do believe, and I do care, and so I empathize with the victims of the threat, which is very unpleasant and not something I want to feel. (Although others have different preferences, for example Shannon & I have very different feelings about empathizing with other's pain).

(a) and (b) are bad cinema, (c) is disturbing, and so that which is not disturbing must be bad cinema.

Or must it? After all, if the ultimate goal of a movie is entertainment, the fact that I didn't enjoy this experience means that perhaps effective depictions of evil, while good in one sense, are not good in another. Those other movies, by being less engaging, made for a better viewing experience. Emotions are powerful things, and when it comes to subjects that invoke unpleasant ones, I'd rather be less gripped so that I can experience the story on a more abstract, intellectual level. YMMV.

So for me, at least, The Dark Knight was not good entertainment. But it was definitely one hell of a movie.