I agree. Expectations were enormously high given that Nolan was producing and frankly because comic book movies had been well received lately. I mean good grief, Captain America and Thor were solid films and received great reviews. Now you take an icon like Superman, match him up with TDK creators, give it a great budget and promise dynamite action....who wouldn't expect the movie to take off?
But poor WOM and bad reviews can hurt a film. I think what we're seeing for the most part is that there is huge interest in the character. People were going to go see this movie no matter what. But poor WOM prevented some repeat business. Its not only critics who didn't like the film, a lot of fans and moviegoers felt the same way.