When Iron Man came out I was honestly not as excited as I could have been. I did not know who the hell Robert Downey Jr. was and my popularity never was with Iron Man, or his stories. Honestly though, the casting was perfect, and you could tell that they all tried hard in succeeding in their roles as their characters especially Robert. He IS Iron Man and to me, will always be. There is nobody else that could have captured that asshole yet honorable essence that Tony Stark has, and wow, I certainty was blown away at how well he did.
I enjoyed the way the friendship played out between Tony and Rhodey(played by Terrance Howard) and was extremely moved by how Terrance had total sincere emotion to his character and his care for his best friend. He was impressive by my standards and I was disappointed to not see him return in the sequel, but that is a different story all its own. As far as I can tell, he was as reliable in his role as Downey jr. was.
To me, the roles of Pepper Potts and Obadiah Stane did not really appeal to me, but to my belief, were portrayed excellently, and with great care and passion, this film was directed by Jon Favreau, who equally shared the same care as his actors, in making one of the best films in CBM history. For last, the special effects were the most amazing I have ever seen before in any film, and in my opinion, nothing will ever beat that.