Overall I think the Movie could have been better, but it was worth the entertainment value that you can expect from a Marvel comic action based Movie. Disney seems to do an excellent job with the artistry of putting together strong characters that can relate well with one another. At least well enough to pull the story off. Humor offsets the tension in the film which you can also expect from Disney. I would have given the story higher marks if it didn't drag in some parts during the 1st half of the Movie. It's a matter if the screen writers could have done a better job at developing relationships with the characters with out so much film time. I don't know if that could have been possible, so I don't want to be too critical.
The actors also did an outstanding job of selling their roles to us Marvel fans as believable super hero's. I don't know if you can say one actor did a better job than the other. The casting seem to fit well with each personality. Well done to the casting crew! The actors would have received an excellent grade from me if it were not one small annoyance that I have that bothers me...Robert Downey Jr. has one of the biggest talents in tinsel town. I love his powerful charisma and quick wit. I just think he is a little over the top and is too fast with delivering his lines. If he toned it downy just a little bit, this actor would truly be an Iron man in Hollywood. Maybe I expect him to be perfect, but I think it's because he clearly is one of my favorites.
One other note...All though I was satisfied with all the actors roles, I have to give special mention to Mark Ruffalo's character as Dr. Banner. He truly fits (in my mind) the Jekyll side of the Hulk. And while mentioning that, I will say that was the most satisfying portrayal of the Hulk in all of the Marvel movies.
To sum up the acting jobs, I will just say they were able to portray these Marvel Super Hero's the way I remembered reading them, as a kid when I used to buy them at the drug store for 10 cents. That should show how long Marvel has been around as well as myself.
Pros well paced, great story, great actors, perfect character fit!