Iron Man 2, the sequel to the 2008 blockbuster about the Marvel comic book character, plays it safe with the formula that turned its predecessor into a smash hit. That means it never feels as fresh as Iron Man, but also that you’re likely to have a blast with Iron Man 2 if you enjoyed its precursor.

It is the same mix of mischievous humour, high-octane action and Robert Downey Jr that worked so much magic the first time around. Iron Man 2 reunites director Jon Favreau with Downey Jr as Tony Stark/Iron Man and Gwyneth Paltrow as Pepper Pots, and picks up the story where the first one left off.

Stark is high on public adulation, having disclosed his alternate identity as Iron Man to the world. He cockily boasts that he has “privatised world peace” by turning himself into the ultimate deterrent.

But in the background, new threats and dangers are on the rise. Plotting against Iron Man are a Russian supervillain (Mickey Rourke) with a grudge against the Stark family and a rival businessman (Sam Rockwell). Stark is under pressure from government representatives who don’t want to acknowledge a man’s second amendment right to own a weaponised suit of high-tech armour. And the suit that keeps Stark alive is also slowly killing him.

First, the bad stuff about Iron Man 2. Its biggest flaw is that it lacks the laser focus of its predecessor, which told a simple, tidy story and told it well. Narrative threads sprawl from Iron Man 2 like strands of spaghetti and characters spill over its edges, with many of its plots and subplots left unresolved for future movies.

Viewers who aren’t familiar with the Marvel comics universe might be puzzled by some of the characters that drop in and out of the film, such as Nick Fury (Samuel L Jackson) and Natasha Romanoff (also known as the Black Widow in the comics, played by Scarlett Johansson).

Those two characters are there purely to set up The Avengers, a comic fanboy wet dream that will unite Stark and Fury with Captain America, the Hulk and Thor in one film when it is released in 2012. Be that as it may, the whole subplot about Stark’s recruitment into S.H.I.E.L.D ahead of The Avengers film is an unnecessary distraction in Iron Man 2.

With that major criticism out the way, Iron Man 2 is still as much fun as any Hollywood blockbuster is likely to be this year. It’s the rare blockbuster film that spends enough effort on character to ensure that its action scenes matter.

Perhaps the very best thing about Iron Man 2 is the ensemble cast that Favreau has lined up to give flesh-and-blood to their paper-and-ink inspirations. Rourke is a formidable physical presence, a block of granite with steel-grilled teeth, a tapestry of tattoos, dangerous eyes and a laconic growl. Sadly, he doesn’t get nearly enough time on screen to establish a clear rivalry with Downey’s Iron Man.

Sam Rockwell — one of the best character actors around at the moment — chews up the scenery with some of the best lines in the film as a smarmy, unscrupulous defence contractor.

Don Cheadle, who replaces Terrence Howard in the role, is solid as Stark’s friend, Colonel Rhodes. And Johansson, called upon to do little more than smoulder sexily and look good while wearing a tight cat suit and slapping henchmen about, does so perfectly.

But Iron Man 2 is mostly the Robert Downey Jr show, just like the first one was. Tony Stark, as played by Downey Jr, is one of the most complex and flawed comic book heroes we’ve seen to date. Downey Jr amplifies his performance to make Stark even funnier and more charismatic than he was the first time around.

Narcissistic womaniser, glib clown, compulsive thrill-seeker, eccentric scientist and conflicted man of conscience — Stark is all of these things and more. One can’t help thinking that there’s at least some of the mercurial actor’s own hell-raising past in the portrayal.

There’s also a hint of Howard Hughes, the eccentric billionaire who was the inspiration for the original comic book character. Like Hughes, Stark has a long running battle against government busybodies that are trying to call him to order.

Also on the upside, the special effects set pieces in Iron Man 2 outdo those of its predecessor in every way. The first confrontation between Rourke’s Ivan Danko and Iron Man is spectacular. And while the first film went out with a whimper, Iron Man 2 goes out on a high with a memorable steel-on-steel climactic battle.

The dialogue, too, is even better than it was in the first film, with amusing one-liners spinning out like fire from a Gatling gun. Alongside Christopher Nolan’s Batman films, this is probably one of the most quotable comic book films yet.

Iron Man 2 has a freewheeling charm that occasionally lapses into self-indulgence. That may be a product of the way it was shot, with only a loose script to guide it and plenty of improvisation from the actors. A few scenes are almost as cringe worthy as Tobey Maguire’s dance routine in Spiderman 3.

I can’t fathom why Favreau thought the audience would want to see so much of him on screen as minor character, Happy Hogan. I’d have preferred some more screen time with Rourke or Johansson. And the less said about a drunken Stark in full Iron Man armour DJing a party before a fight scored to “Another One Bites the Dust”, the better.

But in the end, these are minor quibbles. Iron Man 2, like Tony Stark, is breezy, likeable and amusing enough to get away with its bald-faced cheek most of the time. — Lance Harris, TechCentral