I come to the Marvel movie franchises as a newbie. When I was a kid, you were either a Marvel or a D.C. guy. I was a D.C. guy. I followed Batman and Superman. I knew who Spiderman was, but I'd never read one of his comic books. That goes for the rest of the Marvel canon as well.
When the Spiderman movie came out - I have to say that I really enjoyed it. I knew all about the radioactive spider before the movie, so no big surprise.
But then this "Iron Man" guy came along. I'd heard the name, seen the covers - but never got into it. (To be honest, I'm still not "into" Iron Man - I don't buy the comics.) But I do enjoy the movies. Why?
He's cool. He's flawed. And he knows it. Forget the tin suit, I'd watch a Tony Stark movie any day of the week. That's what makes for a great superhero - when his secret (or in Tony's case, not-so-secret) identity is as interesting - or MORE interesting than his Superhero identity.
I've come across a number of pitch properties where the hero derives his powers from the suit that he or she wears. I call these "the magic golashes" - as in, "He can fly when he wears The Magic Golashes". But as soon as he kick them off - he's just a regular guy.
And that's the problem - nobody wants to see a "regular guy". Your hero has to be as amazing and cool in his daily life as when he's in the suit. Bruce Wayne as played by Michael Keaton in the Tim Burton Batman movies (and by Adam West in the 60's TV series) - was boring. The persona only exists as Batman - which frankly - and I hate to say it - is bad storytelling.
Nope. Take it from this D.C. guy - Iron Man is a brilliant character because of who he is, when he isn't in character.