*My definition: A scientist works out the hypothesis, then designs an experiment that will show if the hypothesis proves true or not. The MAD scientist says: "Hmm. I wonder what will happen if I do--THIS! Ha-ha-ha!" (Or, uses themselves as experimental subject--.)
Downey gives a very nice performance as the playboy inventor who is coming to grips with the idea that his work may not all be for the "good guys." There are actually, in my opinion, even better performances: Gwyneth Paltrow as "'Pepper' Potts", Stark's personal assistant, manages to be both appropriately squeamish when helping Stark plug his reactor into his chest, and reasonably under control flipping switches to help defeat the bad guy while the building is coming down around her ears. Part of this, of course, is the character, who, in the comics was always feisty and not a screamer, but Paltrow carrys it off. The usually likeable Jeff Bridges shows a good talent for villainy and enjoys himself an awful lot as the corrupt corporate heavy, "Obadiah Stane".
Good fun for fans of the comics, and enjoyable and accessible for newcomers.
And now for the quibbles. Beware of the spoilers!
One significant way in which the movie was scientifically WORSE than the comic was in the 'raison d'etre' for Stark's bionic conversion. As in the comics, Stark is wounded by shrapnel. In the Vietnam-era origin story, his heart was damaged, and he required a crude external pacemaker to survive, which he upgraded and made the basis of the original powered suit. In the movie's Afghanistan, he also has shrapnel in his chest, but it is one of his own "fiendish inventions", barbed arrowpoints that tend to burrow further into the body with muscular action, eventually causing death. The terrorists' captive doctor (Shaun Toub) implants a powerful electromagnet (!) to hold the projectiles away from Stark's heart. Come ON! Couldn't he just have removed the shrapnel rather than cutting what appears to be a four-inch wide by six inch deep hole in Stark's chest to mount the magnet? Later on, when Stark's new reactor is stolen by Stane, he acts a lot more like a man who's suffering a heart attack rather than having his heart pierced by barbed metal--which probably should have caused instantaneous death rather than being reversible by having the power turned back on.
In the scene where he has Pepper help him change the reactor to upgrade it, she accidentally pulls the magnetic coil out of his chest, then drops it on the floor. Stark then has the new reactor plugged into SOMEthing inside his chest (but what?) and puts in the new reactor without replacing the electromagnet--which was supposed to be the point of the whole thing.
The entire Iron Man suit runs off the arc reactor implanted in Stark's chest, but there are no visible connections between that unit and the suit, so how does it get power? Induction? Doesn't seem like a very good idea next to one's heart--.
Oh, well. In some ways, issues like that just add to the fun, giving us nerds something to argue about.