I don't know if you have read Iron Man in the last 4 or 5 years but the Iron Man character has been radically transformed. He used to be depicted as a humble and heroic scientist that was physically limited to a wheelchair or physically weak that required his armor to survive. Now, they have made him this arrogant playboy and a major leader in the Marvel universe. Marvel has made Iron Man a much more pertinent character in their universe. He is not only the leader of the Mighty Avengers but the director of Shield. The movie is capturing this new Iron Man. The movie is based in part on the animated Iron Man film that came out last year as well so you can check that out if you want to know what the film is like
My biggest problem is they cast Robert Downey Jr. as Tony Stark. There were so many better options. I think Tom Cruise would have made a much better Tony Stark and I'm not a big Tom Cruise fan but his arrogant yet intelligent and self assured disposition would have fit Tony Stark perfectly.