It wasn't a bad film. In fact, I enjoyed it. It's just the best "superhero film" I've seen is Ang Lee's The Hulk. That film got so-so reviews, because it was too cerebral. I think one review said it was like having Alfred Hitchcock direct a Super Mario Brothers game.
While not cerebral, I don't think this film'll work with it's target audience, because Captain America isn't all that "superhero-ish." I mean Captain America effectively gets injected with steroids (that's a good message to be sending kids, isn't it), and is sent in to battle with a Frisbee. Oooh how impressive. If I were a baddie, I'd really scared of that! I rather suspect that teenagers, who are the main audience for this sort of film, are going to seriously underwhelmed by that approach.
In short, thinking adults might enjoy it (though why they'd go and see it is beyond me), while pimply teenagers might go "Ummmm....."