I didn't care about heady things or depth or anything of the sort going into this film. But I still expect to at least care a bit about what's going on. The plot was boring -- by that I don't mean that I hated the movie because it didn't have a deep plot. You can have a pretty basic story that is still interesting and worth your time. Kind of like Aliens. There's nothing deep or perplexing or psychological about Aliens, it's just well written with good characters.
Or, something closer to home even, like Spider-man 2. Not a deep story. But I felt that the character work was extravagant and embraced the true themes of what makes comic book characters compelling. That film didn't have a lot of action in it, but when the action did come, I cared about it and this turned into me finding the action to be thrilling. The Avengers has like 20 minutes of city blocks getting destroyed and all this fucking MONEY up on the screen and vuvuzela shit blasting around...
And then Spider-man 2 has this part where he pours all of his strength, every ounce of his life into stopping a speeding train full of passengers. After this, you get a great scene of the people on the train lifting his body across them, with all of them promising that they won't reveal who he is. In The Avengers you get a similar scene after the city mayhem of people talking about how cool they were and this and that. However, what works in Spider-man is that most of the film is spent watching Peter struggle with what he wants to do: be normal, or be the hero that people need. You got real character development and struggle there, so when he saves everyone from the train, it's actually emotional and meaningful because of everything that came before. It all ends up coming together in a really fantastic way.
For me that's what a "true" comic book movie is. Not a bunch of fucking pointless CG action scenes that mean squat. For me it's about character development, inner struggle, all that bullshit. I was very bored all throughout Avengers because it lacked soul. It didn't give me a reason to care about one thing. Having a paper thin story or one without a lot of depth is fine as long as there's some charm and soul beneath. Some heart. I would strongly argue that this movie had none.