His suit may be iron, but he’s still got feet of clay. Tony Stark may not be the same narcissistic jerk he was at the beginning of Iron Man two years ago, but that doesn’t mean he’s someone completely different either. The road to redemption is seldom so straight as that.

There’s a scene in Iron Man 2 in which Tony makes an extraordinary effort (extraordinary for him) to patch up a quarrel with his long-suffering personal assistant Pepper Potts. “Did you bring me strawberries?” she asks with only vestigial incredulity, and so, of course, we know that she’s allergic to strawberries. Tony, though, sees the silver lining: “I am getting better at this — I knew there was a correlation between you and strawberries!” He’s trying to have the thought that counts.

Jon Favreau’s Iron Man was something of a surprise hit, a popcorn conversion story with the shiny chassis of an efficient summer blockbuster and the flighty soul of a screwball comedy. The sequel is much the same, only more so, and improves on the original, in my book. (That may put me in the critical minority, but I think the original was overpraised by some, and now the sequel, perhaps in reaction, is being underrated.)

Iron Man wasn’t a perfect movie, but its energy came from a nearly perfect power source: Robert Downey Jr.’s crackling performance as an action hero with a difference. Almost as crucial was the franchise’s secret weapon, Gwyneth Paltrow’s Pepper Potts, a heroine as self-possessed and discreet as her boss was fickle and self-indulgent.

What Iron Man most crucially lacked, and the sequel offers, is a worthy antagonist for Iron Man. Jeff Bridges’ Obadiah Stane in the original was an effective foil for Tony, but his transformation into the armored super villain known in the comics as Iron Monger wasn’t especially convincing, and the third-act robotic smackdown was anticlimactic. The real climax, in fact, came in the final heartbeat of the film with four electrifying words at a press conference: “I am Iron Man.”

That’s where Iron Man 2 begins, and in this new world, Tony “Iron Man” Stark is the world’s biggest celebrity hero. There are faint echoes of Steve Jobs and Bono in his tech hero-rock star-global do-gooder persona, but analogies limp; Iron Man’s stature is without parallel on the real-world stage.

Operating unilaterally outside government channels, Iron Man eases international tensions and cools global hot spots of violence and unrest. “I have successfully privatized world peace,” Tony insists at a Senate hearing, responding to an attempted government takeover of what one senator calls “the Iron Man weapon.” Tony glibly demurs: “That is not an accurate description of my device. … I define it as a high-tech prosthesis.” Upon such technicalities Senate hearings stand or fall.

In his other suit, Tony Stark reboots his father’s brainchild, the Stark Expo, a global technology event in Queens’ Flushing Meadows Park (site of the 1939 World’s Fair). When Iron Man touches down at the expo to deliver the keynote, de-armoring amid pyrotechnics and a lineup of “Ironette” cheerleaders (in outfits about as suggestive of the armor as such, um, suggestive outfits could be), the crowd goes wild.

World peace and better living through technology: In Tony’s mind, this is the Stark family legacy. But Camelots are never as shining as their architects intend.

Tony now has a social conscience, and his former casual womanizing seems to be a thing of the past (as far as we know). In some ways, though, his behavior is more erratic than ever. Pepper is horrified when he donates his entire collection of modern art to the Boy Scouts (“It’s a good cause,” he says defensively). On another occasion, he risks life and limb on a racetrack in Monaco.

Beyond this unpredictable behavior is a secret: The chest implant that keeps Tony alive and powers the suit is slowly poisoning his body. Then there’s the dark secret Tony doesn’t know about: An unknown enemy watches his success from afar, nursing an old grudge. “You come from a family of thieves and butchers,” Ivan Vanko (an intimidating Mickey Rourke) tells Tony in one of the movie’s most thoughtful lines. “And like all guilty men, you try to rewrite your history — to forget all the lives the Stark family has destroyed.”

Working in conditions not much better than Tony’s original workshop in the terrorist-occupied caves of Afghanistan, Vanko, a gold-toothed, tattooed Russian, fashions a high-powered gladiator suit that puts him in Iron Man’s league, or close enough to prove his point: The Iron Man tech isn’t as unique as Tony claims.

Good thing Vanko doesn’t have Tony’s resources, or he’d be even more dangerous. Oh wait, I forgot the other antagonist: sleazy industrialist Justin Hammer (a priceless Sam Rockwell), who’s like a cut-rate Bill Gates to Tony’s Steve Jobs. The unctuous Hammer may not have the genius of a Stark or a Vanko, but he’s got the resources Vanko lacks, and he woos the taciturn, dangerous Russian like a bow-tied freshman bent on taking a Goth biker chick to the prom.

Hammer and Vanko’s uneasy dance rivals Tony and Pepper’s banter for Iron Man 2’s funniest couple, which is saying something. The screwball vibe is even more pronounced in the sequel, with wittier dialogue and even more deadpan delivery.

There are casting changes. Don Cheadle effectively replaces Terrence Howard as Tony’s military buddy Jim Rhodes. (“I’m here; it’s me. Deal with it,” Cheadle says by way of introduction, speaking as much to the audience as to Tony.) In the comics, Tony’s Achilles’ heel was drink, and when he fell off the wagon, Rhodey was obliged to don the suit — and even to smack down his friend. The film shrewdly transposes Tony’s “blood toxicity” troubles to the suit, but at a birthday party he believes will be his last, Tony does get sloshed — while wearing the armor no less — and Rhodey must step up to the plate.

Scarlett Johansson joins the cast as a femme fatale who calls herself Natalie Rushman and ostensibly works for Stark Industries, although few people will be surprised to learn that she too is hiding something.

While her role mostly involves standing around looking good (and, in a big set piece, looking even better not standing around), her presence here, along with Samuel L. Jackson’s government intelligence honcho Nick Fury, is part of a franchise crossover project building toward an ensemble film featuring Marvel’s Avengers team (which will probably include the Hulk, Captain America, Thor and Black Widow as well as Iron Man).

Natalie is supposed to be a complicating factor in Tony and Pepper’s relationship, which is already complicated enough. But Pepper continues to ground the franchise as well as her boss — even if, in a startling turn of events, he isn’t her boss any more. There may not be many actresses you would want to see the hero wind up with instead of Scarlett Johansson, but Paltrow is one of the few.

Steven D. Greydanus is editor and chief critic at Decent Films. He also blogs at NCRegister.com.

CONTENT ADVISORY: Much comic-book action and mayhem; brief fatal violence and bloody aftermath of a deadly attack; limited profanity and some crude language; suggestive dialogue and innuendo; a scene of drunkenness and operating dangerous machinery while intoxicated; a couple shots of a woman in states of undress (nothing explicit); a production number with scantily clad cheerleader-type dancers. Teens and up.