Robert Downey Jr. IS Tony Stark. His portrayal of the troubled, egotistical Tony is spectacular in this newest film. It has the same hilarious writing for our Iron Man, with memorable scenes with the whole cast. Into the plot, I believe the use of the Mandarin in marketing is a cheap trick with a hollow character that disgraces the image of the Mandarin - in classical comic book lore. However, audiences will be surprised to see Ben Kingsley take what was given to him and make it his own. He does his best with the character and to his credit there is no flaw with him. "AIM" is the villain that "you didn't see coming" and while the movie as a whole filled out nicely, the problem with the movie as a whole was a miscommunication of who the villain is or is not (think a sloppier duo of Spider man 3).
In all, the movie is wonderful with another brilliant performance by RDJ, but bogged down by a surprise twist that is more disappointing than anything else. Here's to hoping Tony Stark will return!