*Disclaimer: towards the end there is a bit of a spoiler.*
What a grand entry into the comic book movie genre. Having itself become a sort of sub-genre of the Sci-Fi/Fantasy genre it's nice to see a movie with great balance of staying true to the inspiration and becoming original and fun for non-comic readers. Downey Jr. is one of the best cast roles in any comic book movie. He is pitch perfect as the insatiably auspicious, playboy genius Tony Stark. With the right amount of arrogant confidence and sarcastic wit he is a great representation of a man who takes full advantage of his billions of dollars yet finds himself seeking to help others. Opposite of Bruce Wayne's front of enjoying his billionaire status Stark not only enjoys it but enjoys it over dramatically due to his having everything he could ever ask for. The supporting cast is wonderful as well, with Howard, and Paltrow doing wonderful in their representations of the friendships with the slightly neurotic Stark. Howard plays Colonel Rhodes very well, with his responsibility a sharp contrast to Stark's "go-with-the-flow" attitude. The character's drinking problem was subtly hinted at and played off well. Paltrow is a wonderful Pepper Potts, Stark's right hand woman, with her clarity of vision and underlying loyalty never for a second overplayed or underplayed. You can tell the feelings between them run deep, and the chemistry between Stark and Potts is great. Bridges is fantastic as Obadiah Stane, with his sinister villainy appearing slowly throughout the arc of the film.
The plot is well progressed and moves along at a great rate. For being a little over two hours long it didn't feel that long at all. In fact it felt just right. I'm glad for that, sometimes comic book movies either are over way too fast and you feel like you were a bit jipped or they drag on, like X-Men 3. ILM never ceases to amaze with their spiffy looking special effects. From the first crude suit to the wonderful Mark 3 he pilots at the end of the film. The conversations between Stark and his robots was great. The transition from a real Jarvis to a computerized version of the butler worked well. I also think it was a good choice since Batman has Alfred another cool butler would look like a slight rip off even if that's not the case. The weapons were cool, and realistic enough to not make you lose interest. All in all a very solid film in general.
Spoiler Section: The references to the Mandarin are subtle enough for fans to enjoy without beating people over the head with them. As a fan it was very evident that "The Ten Rings" had more meaning than a simple terrorist cell, as well as the prominence of the ring on the leaders hand and the references to the Mongol empire. Samuel L. Jackson is great as Nick Fury S.H.I.E.L.D.'s head of operations, any fan will know that in the Ultimates it's quoted that if they ever made a movie about the Avengers Sam Jackson would play Fury, who is drawn to look like Jackson in the Ultimates mythos. I think Marvel Studios has finally gotten a handle on making good comic films...we'll see how this new Hulk movie stands up to the wonders of Iron Man. I would say this is the best Marvel movie made thus far, surpassing even Spiderman 2. If Hulk is good, then I can't wait for Thor and Captain America and once they have those, an Avengers movie will in fact be possible. That could be pretty dang sweet.