If the hulking machines from Transformers jumped celluloid to battle the monstrous title character from Godzilla, the resulting carnage would closely resemble the computer-generated sound and fury of Pacific Rim.

Guillermo del Toro's sci-fi action adventure takes a tantalisingly simple premise - giant robots versus gargantuan aliens - and expands that idea into a soulless exercise in technological might over emotional matter.

It's difficult to believe the writer-director of Pan's Labyrinth and the quirky Hellboy saga has surrendered all of the humanity, which underpinned his previous work, to oversee what is essentially 131 exhausting minutes of wanton destruction.

The script, co-written by Travis Beacham, is a wasteland of two-dimensional characters and hoary cliches, replete with the obligatory stirring call to arms against the extra-terrestrial invaders: "Today, we are facing the monsters and bringing the fight to their door... Today, we are cancelling the apocalypse!"

Grown men of every conceivable nationality pump their fists in the air, whoop and holler, energised by the titanic battle that lies ahead.

Audiences will simply be glad that there is just the final showdown to endure before the end credits roll.

A protracted prologue establishes the emergence of alien creatures known as Kaiju from a temporal rift on the sea floor.

Humanity responds by creating the Jaegers - 25-storey tall robots operated by two pilots, whose minds are melded by a neural link known as The Drift.

Raleigh Becket (Charlie Hunnam) and older brother Yancy (Diego Klattenhoff) are ace pilots of the American robot Gipsy Danger, but their run of victories comes to a tragic end at the claws of one particularly vicious Kaiju.

Five years later, Stacker Pentecost (Idris Elba), commander of the Pan Pacific Defense Corp, approaches Raleigh to step back inside the Gipsy Danger with a new co-pilot.

"I was still connected to my brother when he died. I can't go thought that again," whimpers Raleigh.

However, ballsy protegee Mako Mori (Rinko Kikuchi), who is battling private demons, catches his eye and they forge an intense bond that might swing the balance of power back in favour of mankind.

Pacific Rim concentrates on the digital effects and thunderous action sequences at the expense of the characters and their relationships.

The hokey science behind del Toro's vision is a muddle and occasional forays into comedy, courtesy of two madcap scientists (Charlie Day, Burn Gorman) and a black marketeer called Hannibal Chau (Ron Perlman), sit awkwardly next to the deadly serious business of monster mashing.

Hunnam is a bland, all-American hero, who dutifully flashes his naked torso in early scenes to create a spark of sexual tension with Kikuchi.

Regrettably, their on-screen chemistry is inert.

In the absence of protagonists we can care about, del Toro's film reduces to an incomprehensible and noisy blur of rumbles on land, sea and air.