My experience with the Batman movies has been pretty much the same--in general they seem to me to be dark but lame, and really boring when not deeply disturbing. (And I don't generally like "disturbing" films.) For me, just once of "The Dark Knight" was enough to last a lifetime--I'm not sure why that movie was so popular, really.
But if you're now feeling defensive about Batman, let me get in one more thought. I heard once in a lecture (about da'wah, actually) that Batman was a man of few words--especially compared to his enemies, and namely the Joker. And that the writers of Batman tried to emphasize this point. Using just a few words--being concise--can be more weighty than "watering down" the meaning of a statement with many more words.
It came to my mind recently since I saw someone on a forum with the behavior of the Joker--all talk, no meaning, frequently jumping topics or changing the subject when answered. You have to kind of step back to try and look at the big picture, then be as pithy as possible. Since I've seen many people who attack Islam to have this characteristic (talking too much, using words to trick an audience) and seen people respond to it with an equal number of words (usually unconvincing,) it's worthwhile to learn a lesson from Batman.
When conveying the message of Islam, be clear, be concise, and repeat, so the truth does not get lost in the mud and muck being thrown around.