Iron Man 2

An Iron Man sequel was an inevitability the moment Robert Downey Jr. stepped onscreen wearing Tony Stark's signature goatee, in the greatest "well, duh" piece of comic book movie casting since Patrick Stewart's Professor Xavier in X-Men. Almost a "little movie that could" - if it's not odd to say that about a major studio blockbuster costing $140m to make - it arrived without much advance fanfare but waltzed away with half a billion in box office receipts in its back pocket plus widespread critical acclaim.

But while Iron Man 2 benefits from continuity of director, cast (the substitution of Don Cheadle for Terrence Howard aside) and overall feel, it makes its bow in very different circumstances - because now, it's got to live up to the reputation of that mega hit; not to mention the generally-accepted rule that first sequels to good superhero films are usually even better (see: X2, The Dark Knight, Spider-Man 2)

It's disappointing, then, that Iron Man 2 fails to live up to its predecessor's wave of joyous, un-ironic exuberance. The hollow feeling to the whole thing is particularly odd given how right so many of the individual elements feel in and of themselves. The ensemble cast are uniformly excellent - comparable to The Dark Knight, even, albeit generally for different reasons. Sam Rockwell is a particular standout as sleazy Stark-wannabe Justin Hammer (unexpectedly, considering the publicity and posters, actually the film's main antagonist), with Gwyneth Paltrow making the most of a much-improved role for Pepper Potts, and even smaller pleasures such as Garry Shandling's smarmy senator given time to shine.

The action is arguably the element that does improve on the original - whereas in that film many of the in-suit sequences were sky-bound scenes that felt all too video-game-esque, things are rather more grounded and tangible this time out - perhaps helped by Ol' Shellhead having similarly-outfitted foes to scrap with on the ground right from the start, rather than having to wait until the denouement.

There's also more of Iron Man himself this time - and a well-judged balance is maintained by giving plenty of screen time to a de-masked Downey at his charismatic best. Meanwhile, Favreau continues to show strong flair for action set pieces, particularly in an utterly gripping first act face-off with Mickey Rourke's Whiplash at the Monaco Grand Prix.

As for plot, if you take each of the film's threads individually, they all work - Rourke's Russian physicist with a grudge is a strong villain (even if you can't understand what he's saying half the time), while Rockwell's underhand industrialist represents a different sort of foe. Meanwhile, any of the multiple problems Stark has to contend with would make a decent main subplot on their own. There's his public fall from grace, the terminal illness caused by the very device that's keeping him alive, his stuttering relationship with Pepper, and some deep-seated father issues; not to mention the moral dilemma faced by best friend Jim Rhodes (Cheadle).

The problem arises when attempting to find room for all of these disparate elements - it's a classic comic book movie sequel problem that you'd really think people should have learned from by now, but it just keeps happening. In Iron Man 2's case, it ends up being Rourke who suffers - shown to be a truly menacing threat in the first half of film, he's relegated to working in a lab for the second half, before being given a climactic battle that lasts all of thirty seconds.

Aside from everything else competing for attention, there's the small matter of Scarlett Johansson's Black Widow - a strong performance that includes a single terrific action set-piece, but a role that has absolutely no reason to be in this film other to set up the forthcoming Avengers film. Indeed, while scenes with her and Samuel L Jackson's Nick Fury are sure to please the fanboys eagerly awaiting Marvel's mega team-up movie (and watch out after the closing credits for a little more on the crossover front), they represent the biggest threat to the casual viewer's enjoyment, as a good twenty minutes or so are spent on scenes that feel airlifted in from another film entirely.

And therein lies the major problem - while the first film did a superb job of introducing a lesser-known comic book character to a wider audience, the sequel relies more on the viewer already knowing why certain characters, plot points or references should come off as cool or exciting. It's all well and good giving Rhodes' "War Machine" outfit its proper technical name from the comics at one point, or throwing in a less-than-subtle nod to Captain America, but when it's at the expense of giving proper development to Tony and Pepper's relationship, or adequately addressing the legitimate grievance Ivan Vanko (who, curiously, doesn't seem to be named as Whiplash onscreen at any point) has with the Starks, the overall sense of coherency can't help but suffer.

It's a difficult film to dislike - thanks in no small part to Downey's effortless charm - and you suspect that had the first film been of this quality, it still would have been a modest success. But the reputation already established by the franchise, not to mention the other big comic book movie that's already preceded it this year (Kick-Ass), serve to make it a disappointment by comparison.