Iron Man 3 review: A big hand for Downey Jr, but movie lacks dramatic mettle

Iron Man 3 shows up both the glories and the extreme limitations of the superhero summer blockbuster genre. Director Shane Black and his British co-writer Drew Pearce work tremendously hard to bring humour, irony and complexity to their screenplay, even if they are defeated by the sheer superficiality of their source material.

Robert Downey Jr is as appealing as ever as Tony Stark, the playboy/engineering genius, saving the world in his iron suit. The film serves up plenty of spectacle – explosions, chases and brilliantly choreographed feats of acrobatics in which Downey leaps hither and thither like an iron-clad Douglas Fairbanks. As in The Dark Knight Rises, in which Tom Hardy's Bane terrified America, there is again a very menacing villain (Ben Kingsley's The Mandarin), who seems like a mix of Nosferatu, Fu Manchu and Osama bin Laden.

The problem is that the storyline is still B-movie stuff. The final-reel stand-off between the hero and his antagonist could have been borrowed from any Buster Crabbe sci-fi film serial of the 1930s. There is a sense that the film-makers don't know how seriously to take their own movie. As in Kiss Kiss Bang Bang (2005), the spoof film noir he made with Downey, Black can't resist sending up his own characters.

The more tongue in cheek Iron Man 3 becomes, the less dramatic tension it possesses. Jokes about Croydon, British football and Downton Abbey are funny in their own right (even if they may pass over the heads of many American viewers) but they puncture the sense of menace that the film has in its early scenes, when The Mandarin is humiliating American broadcasters and politicians.

Iron Man 3 is trying very hard to be what the Hollywood marketeers call a four-quadrant movie – that's to say, one that appeals to every demographic. Amid all the gadgetry and hardware, the film seeks to position itself as a romance. At the same time that his compound is being blown up and he is trying to save the free world, Tony Stark still finds time to call his girlfriend, Pepper Potts (Gwyneth Paltrow), "the one thing I can't live without", as he calls her. For her part, she's a little jealous and perplexed when a woman from Tony's past, the beautiful botanist Dr Maya Hansen (Rebecca Hall), turns up at the door.

This is also a kids' movie of sorts. When Tony is hiding out in small-town America and trying to rebuild his armour, he befriends Harley (Ty Simpkins), a doe-eyed boy whose back shed briefly becomes his base of operations. Harley's presence is disconcerting given the scenes when the film veers into nasty, Eli Roth-style territory, with characters trussed up in dungeons and tortured by mad scientist Aldrich Killian (Guy Pearce in pantomime villain mode).

Downey is a brilliant actor who somehow manages to portray Tony Stark as traumatised without losing the character's laidback and comedic quality. His approach is the antithesis to that of Christian Bale in the Batman films. Whereas Bale is saturnine and intense – a superhero carrying the weight of the world on his shoulders – Downey is playful and Chaplinesque. The Iron Man franchise – along with his role in Sherlock Holmes – has revived Downey's career after the drug-related problems he endured a decade ago. He is now a very big star.

Even so, watching a film revived this week, Jerry Schatzberg's Scarecrow (1973), starring Gene Hackman and Al Pacino, you can't help but regret the lack of opportunities that Downey has had to stretch himself as an actor. He would have been a perfect fit for the character-driven dramas directed by the like of Schatzberg, Bob Rafelson, Hal Ashby and Robert Altman (with whom he made Short Cuts in 1993) in that golden age of early 1970s American cinema.