C'mon, guys, don't take these sales seriously. Almost everyone who went to go see Batman was there because they wanted to see it, for whatever reason. This movie was way overpopulated by fangirls, either those too young too go alone and had to take at least one parent, or older girls who threatened to break up with their boyfriends if they didn't go see it with them. Trust me one this one, sales were easily 2-3x what they would've been if everyone who had been there actually wanted to be there.
As for comparing the two, I saw TDK twice and enjoyed it both times. I tried reading Twilight once a couple years ago and gagged at both the plot and writing style. I can't even imagine how terrible the movie must have been.