Yeah, but that's because Hulk was sharing screen time with everyone else. They used him sparingly, and whenever he actually did something, it mattered. There was weight to his actions.
When you do an entire movie about Hulk, it becomes diluted to the point that he's just another action hero, and you stop appreciating him for what he really is.
I think all of these characters work better in bite-size doses, complimenting one another. That's why it's going to be really tough for any of their subsequent solo outings to generate the same kind of fervor as The Avengers.
Like Toe said, I don't give a shit about seeing another Thor, or another Captain America, or even another Iron Man, which is already a sure thing. What kind of bullshit contrivances will they have to come up with to explain why these guys aren't calling in their bros for backup?