Sequels are the most difficult movies to get right. Fickle audiences are anticipating more of what they loved in the first flick, but don't want it to become repetitive. On the flipside they also expect it to be fresh and innovative without it feeling like an altogether dissimilar movie from the original. Trying to find that balance is an extremely tricky thing and most don't succeed. Where does IM2 fit in? It's not in the higher echelon of action sequels alongside The Dark Knight or X2, which bettered their predecessors, but it's definitely not far off and that's no easy feat.

Justin Theroux's screenplay is crammed with a plethora of plot strands and for the most part – minus a partially neglected Tony / Pepper subplot here and a wasted opportunity with Vanko there – he manages to juggle them quite effectively. The biting social commentary from the initial film is back in addition to the trademark casual humour not seen in other comic book adaptations, however Theroux has expanded the Iron Man franchise with a slightly more light-hearted approach, undoubtedly due to the burgeoning Marvel movie-universe that is currently being formed. Subsequently there's a much stronger focus on the collective Marvel effort to come in the future, thanks to a larger part for Nick Fury (Jackson) and a couple of teasing moments (make sure you stay until the end of the credits) that hint at other characters looming nearby.

Returning in the director's seat is the ever-surprising Jon Favreau, once again helming with confidence and flair. His handle on the action set-pieces increasingly gets better, despite a vaguely underwhelming climactic showdown, with the clash at Monaco's F1 Grand Prix and ruckus at Tony's Malibu mansion the highlights. The special effects team greatly aid Favreau as the CGI is practically faultless; the diverse machinery on show is photo-realistic ensuring the fight and flight sequences look amazing. Sans computer effects, a lithe Johansson rumbling with a handful of Hammer's henchmen will have you in awe, not just because of the outfit worn by Johansson but due to the excellent fight choreography and the fact that most of the stunts were performed by the actress herself.

Portraying our uniquely cavalier protagonist, Downey Jr exudes charisma and style yet again. His cocky, eccentric exterior becomes a tad monotonous but never reaches a level that decreases his likability. Unexpectedly the cast member that challenges Downey Jr to best on screen is the equally peculiar and compelling Sam Rockwell. He makes what could have been a smarmy, one-dimensional villain into a humorous and engaging tyrant who even manages to outdo Tony in the comedy stakes. Elsewhere Rourke makes for a suitable tattooed Ruskie, Paltrow and Johannson offer sweet and sexy respectively and Cheadle fills the boots left by Terrence Howard gratifyingly. Kudos to Cheadle and the filmmakers for making the 'new' Rhodey's entrance a memorably quick-witted in-joke too; they swiftly dispel the audiences concern of having a different actor in the role.

A rousing follow-up that very nearly matches the brilliant first instalment and will leave you keen for more Iron Man, whether in his own movie or not.

4 out of 5 (1 - Rubbish, 2 - Ordinary, 3 - Good, 4 - Excellent, 5 - Classic)