It seems Iron Man can't be discussed without comparing it to other superhero movies. At least, I can't think of it any other way. But unlike most of the other superhero films over the past decade, Iron Man presents a sexy, confident hero. Iron Man will kick you ass with his repulsor rays and he'll love it. That scene in the trailer where he shoots the tiny rocket at the tank, then turns and slow walks toward the camera with the explosion behind him? That's not just summer action movie cool. That's Tony Stark cool. He acts like that even when nobody's around to see him, because being a superhero is the world's coolest hobby. Sure, he's got some kind of guilt over years of weapon profiteering, but that's just so he doesn't look like a dick. He loves having a high-tech suit of armor and being able to fly in and act the hero, and the movie knows it.
It's easily the best version of Tony Stark ever. Robert Downey, Jr. has personified what Iron Man always should have been.
That's the thing with this movie. It doesn't have as much obligation to the source material because how many definitive Iron Man stories are there really? "Demon in a Bottle"? That's it. And even that is not so much a coherent narrative as it is a bunch of traditional superhero stories with a subplot about alcoholism. So this movie gets to come in and do whatever it wants with the character, but the glorious part, the thing that really bodes well for future Jon Favreau/Marvel productions, is that instead of just taking the concept and going in a new direction, the movie nails the essence of the character in a way the comics never could.
And it Jeff Bridges gives great Obidiah Stane. Same with Paltrow's Pepper Potts. All are perfect.
Even if the movie lags a bit, it lags by focusing a bit too much on Tony Stark's technology fetish, and that's not such a bad choice. He is obsessive, and his tinkering can slow down the movie, but that's what that character is about just as much as he's about flying low over a carnival just to show off.
Iron Man isn't revolutionary or ground-breaking or innovative. It's just really good. You'll like it.