The summer movie season launches with a sophisticated superhero movie that doesn't pander to the sensibility usually associated with the genre. The downside: Iron Man doesn't exhilarate or take hold of the imagination. More emphasis is placed on character than action, a probable -- though not inevitable or uniformly positive -- result of casting Robert Downey, Jr. as playboy industrialist Tony Stark. Personality and effects-driven wows aren't mutually exclusive of course. Yet by tipping toward the former, this rendering of the Marvel Comic introduced in 1963 remains a tad dry. The dumb teenager in me was grateful he wasn't being talked down to, but he wasn't blown away either.

Possessing Dick Cheney's political outlook, Hugh Hefner's lifestyle and knack for self-promotion, Bill Gates' ruthless entrepreneurial spirit, and the scientific and engineering prowess of an MIT professor, arms merchant Stark is considered by his detractors to be the biggest mass murderer in U.S. history. A suavely avaricious, hard-partying bachelor billionaire -- orphaned like his fellows Peter Parker and Bruce Wayne -- he invents and then supplies the world with weapons.

In the opening scene, we see the Scotch-on-the-rocks he's holding before we glimpse Stark riding in a US military Humvee in Afghanistan. He's there to unveil Stark Industry's latest creation, the Jericho missile; and as he's teasing the admiring soldiers escorting him, we know the light, jocular atmosphere will soon be interrupted. What we don't realize is that it will never be dispelled entirely.

The convoy is attacked and Stark severely wounded. He wakes up in a cave with a car battery connected to a hole in his chest. According to the Afghani physician (Shaun Toub) who saved his life, it will prevent the shrapnel discharged by one of his own bombs from traveling to his heart. When the terrorists holding them order Stark to make missiles, he builds a mini nuclear reactor to replace the device the doctor has rigged up. This neat piece of technology will keep him alive and lead to the birth of Iron Man.

Instead of a conventional missile, Stark and the doctor construct an armored suit that enables him to escape after three months in captivity. The experience triggers an epiphany. Much to the chagrin of his business associate Obadiah Stane (Jeff Bridges), Stark devotes himself to promoting peace and leaving an honorable personal legacy. This puts Stark Industries at risk and eventually entails destroying some of his own weaponry in the field.

Becoming the do-gooder in the diving bell does enhance Stark's stature in the eyes of his priggishly loyal assistant Pepper Potts (Gwyneth Paltrow). And he suddenly realizes that she's fetching in more ways than one. It's not clear who is more enamored of Stark, his leggy major domo or his admiring friend and liaison to the U.S. Military, an Air Force officer named Rhodey (Terrence Howard).

As Stark subverts the efforts of his company, one of the coziest relationships in the history of the military industrial complex is threatened. Rhodey doesn't seem to mind, for now at least. His dormant jealously might be incorporated into subsequent scenarios (and may already have been, since many drafts of the sequel must already exist). The overtly priapic essence of this and every other superhero saga is upheld when Stark faces off against his mentor Stane. Casting Bridges, who looks like a textbook Mephistopheles with a bald pate and bushy beard, heightens the sense Iron Man is more about character development than special effects.

Downey acquits himself well enough during the action sequences, there just aren't enough of them and the existing ones could use a boost. There's a relatively dull middle stretch of thirty minutes or so when Stark is hunkered down in his Malibu pad perfecting his invention. The climactic clash of the Gigantors Stark and Stane is a bit skimpy.

Few actors can exude as much distinctive personality, vocally or physically, while hidden beneath a suit of gold titanium alloy. Downey's offhand charm and wry, understated delivery (particularly in the banter between Stark and Pepper and the computers that assist him) are enjoyable and certainly unusual in this domain. Yet it's unclear how far this energy can propel the franchise.

Tony Stark is heroic because of what he stops doing more than for what he actually does over the course of the movie. The resulting imbalance suggests the filmmakers are biding time until the second installment. There's a difference between overdoing the special effects and enjoying them. To the movie's benefit and detriment, director Jon Favreau and company have more fun with the man than the machine.

(Released by Paramount Pictures and rated "PG-13" for some intense sequences of sci-fi action and violence, brief suggestive content.)