Tony Stark is the kind of billionaire playboy I can get behind.

True, Bruce Wayne got there first, but when you picture him on his birthday, you can only really envisage him brooding in his batcave, thumbing his mother’s old jewellery from the night of her murder. Tony Stark, on the other hand, is more likely to be found collapsing drunk as the DJ at his own penthouse party, but not before having Scarlett Johansen drape herself over him, declaring that – were it *her* birthday – she’d “do whatever I wanted to do, with whoever I wanted to do it with” [beat] *seductive stare*.

No one likes a party pooper, Bruce.

Still, Iron Man 2 isn’t very good. Naturally, to suggest Robert Downey Jr acting out his vigilante fantasies could be anything less than basically enjoyable would be foolish; it’s simply inherent to the form. But after a first film that exuded youthful confidence and delighted us with a sharp script, this sequel seems content merely to swagger its way to a bloated middle age.

There are problems and delights in equal measure, often in quick succession. The introduction, for instance: on the one hand, the film opens with Stark cementing himself as The Free World personified, aptly dispatching with trouble wherever it might arise. We meet him revelling in his success at the opening of the Stark Expo, proud on a stage of buxom cheerleaders and pyrotechnics. He is at ease with the crowd’s rapturous applause, and the film is quick to recapture the pomp and humour of Iron Man 1: Stark as the man, a playboy prince at work and play.

Yet it also introduces its villain by way of recycled – generously, ‘referenced’ – scenes from that film: deep in Siberia, a father is on his death bed and tells his son of his secrets, the Stark Expo playing ominously on the small screen behind. They whisper together in Russian, the rough translation amounting to “Son, you will, through the power of vodka and montage, build your own Arc Reactor to challenge the imperialist might of Tony Stark.” “Okay Dad”.

And so begins the farcical introduction to Ivan Vanko, Mickey Rourke’s approximation of a comic book villain at a He-Man convention, all bursting pecs and cod-pieces. His scenes are depressingly outmoded, a montage lazily recalling Stark’s own suit-building sequence segueing into one of *those scenes* of him screaming in despair, fists shaking as the camera moves skyward and looks down. It turns out costumes of awesome power can be forged only in the fires of your cave whilst you bitterly look at press clippings of your rival. Must. Solder. Through. The. Night.

More rewardingly, the film explores new territory in the ramifications of Stark Industries having access to military-grade technology, with a series of hearings amusingly culminating in a grizzled senator compelling a whimsical Stark to hand his suit over to the Government. Whilst not obviously fertile ground for an action film, the thread develops the film’s key partnerships and rivalries: Colonel ‘Rhodey’ is the middleman between Tony and the Military, though it’s difficult to take actor Don Cheedle seriously when, donning the counterpart to Iron Man’s suit, he curiously transforms into Spike Lee droppin’ gangsta. Justin Hammer, meanwhile, is deliciously slimy as Stark’s business rival, up to his neck in government contracts and loving every minute. So compelling is the dynamic between the two of them that poor Vanko finds himself largely relegated to background boogie man.

Director Jon Favaeu apparently made a point of keeping the series as grounded as possible, yet much as the first film seemed fantastical, this not only offers Vanko up as the most unlikely physicist this side of Christmas Jones, but has Tony Stark manufacturing an entirely new element by waving his hands around like it was 1977. It isn’t immediately clear why that’s less credible than tossing off an arc reactor of limitless potential in a cave, but watch and you’ll surely understand.

Stranger still is Johansen as Natasha Romanoff, a S.H.I.E.L.D agent who manages the incredible feat of being fantastically, outrageously attractive, yet utterly redundant. That such words dare to be juxtaposed amounts to a blasphemy from a seasoned voyeur like myself, but it’s true nonetheless: important to the cannon or not, as she slinks around in a figure-hugging catsuit trying to be nonchalant, you feel embarrassed even for Samuel L Jackson, a man whose own contribution extends only as far as a comedy eye-patch.

Amongst all that, there are glimpses of magic, notably in the old-married-couple dynamic of Pepper Potts and Tony that fuels what little emotional resonance the film has, or in an early speech where Vanko equates humiliating Stark to ‘making God bleed’. But for an action movie it’s curiously lacking in action scenes, preferring to focus its limited energies on pointless exposition and technogabble solutions that stretch science-fiction creditability. The little action is intermittently enjoyable, but too often falls into the trap of simply throwing more bodies at the screen, particularly in a climax that wouldn’t seem out of place in Transformers the sequel.

Iron Man was never lacking in such indulgences, but as Tony Stark creates new elements in his basement, a feat sandwiched between lattes and secret superhero clubs, you find yourself rolling your eyes at a franchise that once winked at the audience.