So here we are then. Four years after Samuel L. Jackson turned up at the end of the first Iron Man movie with talk of “putting a team together”, through innumerable script and crew changes and a whole bunch of okay-ish films introducing our various superhuman warriors, The Avengers (or in this country, for reasons we’re still not totally sure of, Avengers Assemble) is finally landing at a cinema near you.

One may be forgiven for being sceptical about this amalgamation of Marvel’s various superhero franchises – after all, it has plenty of factors set against it. First and foremost, it’s a Hollywood action movie, a genre whose output has been consistently sketchy since, well… ever. Secondly, with a galaxy of big stars and a mega-distributor (Disney) behind it, this looks from the outset to be a case of too many cooks spoiling an already unsteady broth and many critics, myself included, have been bracing ourselves for the over-hyped, three-star disappointment of the summer. Well, I think I hear the waiter arriving with a huge portion of humble pie, because I’ll be damned if The Avengers isn’t Marvel’s finest achievement and, Christopher Nolan notwithstanding, the best superhero movie of this era.

Those approaching the franchise for the first time may be a little apprehensive, especially with at least four films worth of background to catch up on, but writer/director Joss Whedon excels in making everything as accessible as possible, no matter what your experience of the Marvel Universe.

Loki (Tom Hiddleston), brother of Thor and all-round nasty piece of work, has arrived on Earth with his eyes firmly on the Tesseract, the unpredictable but powerful artefact that served as Captain America’s major plot device in last year’s film. With the help of a shady new ally, the only thing stopping Loki from using it to take over the world is a bunch of disparate and unpredictable characters of varying power. Sound complicated? Not really. Basically: Source of Ultimate Power + Nefarious Evil-doer + World in Danger = Team of Superheroes Required. The real challenge here is balancing that equation and it’s a task that Whedon succeeds at with aplomb.

With all the huge personalities and massive action sequences required from a film such as this, the biggest threat is if it fails to become the sum of its parts. However Whedon has always been the master of balancing out potentially difficult concepts into watchable material (see Buffy, Firefly and, most recently, the peerless Cabin In The Woods) and here he succeeds again, by not giving any one element precedent over the other. A lesser director might be tempted to give perhaps one hero the ‘lead’ role, turning the entire piece into Tony Stark (Robert Downey Jnr) And Friends, but Whedon spreads the wealth magnificently, turning out a true ensemble piece of the highest order.

Another obstacle expertly steered around by both the director and actors is the potential loss of empathy for the team, but again Whedon comes up trumps, injecting each character with enough heart and personality to endear them to the audience, both as individuals and as a group.

He’s helped in this respect by a solid group of performances, again with each actor never attempting to rise above any of his or her peers. Downey Jnr is, as usual, at his charismatic best as billionaire inventor Stark and Scarlett Johansson provides great substance as Black Widow, holding her own in what is largely a testosterone driven movie.

The highlight of the cast, however, is new arrival Mark Ruffalo, facing the huge challenge of being the third actor in a decade to portray Bruce Banner, the man behind the Hulk. Ruffalo walks the line between previous incumbents Eric Bana and Ed Norton perfectly, who were too athletic and smart-arse respectively, producing a humble, thoughtful Bana, closer to the classic television version of the character and all the better for it.

A common complaint with films of this nature is that they often expend all their energies on one set piece, making the film as a whole a weaker experience, but again here’s that word again – balance. Whedon has made it so that no one part of the experience feels like a too early climax, each set piece perfectly weighted, leading to a superb climatic battle on the streets of Manhattan, which puts anything Michael Bay has done in the shade.

The one phrase that has consistently appeared on Twitter after preview screenings of The Avengers is “perfect popcorn movie” and it’s difficult to argue with that assessment. This is really a masterclass in how to direct an action film. Likeable characters, a simple but engaging plot, superb pacing and set pieces that thrill but never become tiresome, along with some witty dialogue. Fans of Buffy, Angel and Firefly have been worshipping at the feet of Joss Whedon since the late 90s, but, if this is anything to go by, their temple is about to become mighty crowded.

Overall Verdict: What was billed as the ultimate comic book movie turns out to be just that. A rip-roaring, smart, funny action film that ticks every box on its way to becoming an instant classic. If this is the standard to beat in Summer 2012, we’re in for a hell of a year.

Reviewer: Alex Hall