Iron Man 2

By way of preamble, it does its requisite bit of forging and soldering and banging out a setup, but only at the fittingly named Stark Expo do proper Iron Man 2 introductions begin. Exposition might be the only order of this movie’s business: With all the fireworks, the gadgetry, the corporatized idol worship and heavy-duty charm, it finally amounts to a Marvel Studios trade show.

Thank goodness it’s still got Robert Downey Jr. as Tony Stark, the rocket-powered knight in self-styled armor, to guide us through the conspicuous outlay. As expected, he’s in a chatty, romping mood, and about as lovable as an alcoholic billionaire narcissist can be.

But even after the great flamboyant relief of coming out as Iron Man, Stark still has his issues. For one thing, he’s got a problem with his gear: It keeps him alive, but it’s killing him, and not metaphorically. Subbing in sludgy chlorophyll smoothies for his much-preferred cocktails isn’t quite enough. There is the small matter of needing to invent a new element.

Also, Stark’s quest to keep his deadly technology out of the wrong hands has become more complicated. His antagonists are many. They include Garry Shandling as a grasping Senate subcommittee chairman; Don Cheadle (formerly Terrence Howard) as a suddenly adversarial friend and military ally; John Slattery, seen in yellowing corporate-propaganda filmstrips, as Stark’s dead weapon-maker dad; and of course Downey’s fellow near-casualty of 1980s Hollywood, Mickey Rourke, as a seething Siberian exile with an axe to grind and a pair of live-wire whips to crack.

That Rourke’s character’s patchwork of prison tats seems more authentic than his advanced understanding of physics is part of the copious superhero-comic charm — an endowment which also must account for Scarlett Johansson as that new girl, the buxom and mysterious martial artist from the Stark Industries legal department.

We know what this means. At the very least, it means increased personal and professional responsibility for Stark’s put-upon assistant Pepper Potts, played once more with aplomb by Gwyneth Paltrow.

But wait, there’s more: Enter Sam Rockwell as Tony’s squirrelly arms-dealer rival Justin Hammer, a sort of Stark lite; and Sam Jackson as Nick Fury, the head of a covert agency called SHIELD. Marvel Comics completists will observe that hammers and shields are of special importance here, at least as far as franchise propagation is concerned.

We can say that director Jon Favreau is concerned about franchise propagation. With its wily script by Justin Theroux, Favreau’s film is hearty and swiftly paced, but not helped by having so many characters in need of establishment and so few actors on par with Downey’s rapturous timing. Everybody seems happy to be here, yes, but the net effect is of a generously borne mutual strain.

And it’s too bad those menacing, most promising moments — Stark suited up and falling-down drunk at his own birthday party, Hammer’s machines running murderously amok — go without the more thoughtful attention they deserve. Favreau and co. do have a knack for meeting superhero blockbuster expectations. But what else have they got? Guess we’ll just have to wait for next year’s Stark Expo to find out.