This is related to what Javi was saying..but, I don't think the general population knows much about Iron Man as they do about Spider-Man. He's just not as recognizable of a character/brand. But obviously, the film proved to be a success. I just don't think he's nearly as well-known as super-heros like Superman, Batman, Spider-man, etc. (I do realize that Superman isn't a Marvel comic, but you get my point, I hope).
I will probably just wait for this to come out on DVD, not that I really want to anyways, but everyone seems to like it, so I will check it out someday.