First off - nothing about the movie will be mentioned so this will not ruin it for you.
As a long time Iron Man comic follower from the 70's/80's/90's, I think their revamping of the Iron Man "world" wasn't all that bad. They needed to make it a movie franchise and gear up for other films coming out in the Marvel Universe. I overall liked how the played things out and didn't leave me screaming, "That's not how it happened.." like people were in the JJ Abrams version of the StarTrek movie. So on to the good stuff.
I think the biggest positive is also it's biggest negative - Mickey Rourke. I wish they could have included him more in the movie. He was simply a great villain. Sam Rockwell as a not as smooth or charming version of Stark was brilliantly played out. I hope they can incorporate him in the next film somehow.
Don Cheadle played a good version of James Rhodes but I would have loved to have seen a return of Terrence Howard. I liked him better as he looked the part and I believed in him.
Scarlett Johansson/Gwyneth Paltrow looked stunning but you already knew that and Mr. Samuel L. Jackson as Nick Fury was stern and funny at the same time as he is not only a connection to Tony's future but also his past.