It's probably around the two-hour mark of this big, bloated, bombastic spectacle of a sequel that you might start thinking to yourself, why are we doing this again?

Money, obviously. Because Transformers: Age of Extinction - the fourth film in Michael Bay's robots-going-berserk-on-Earth franchise - reeks of it.

The film's reported $189 million budget is obvious from its opening moments in which huge alien spaceships thunder over the planet dropping bombs as beautifully rendered dinosaurs flee from the flames.

It's there when the stars of the show - those gigantic robots known as Autobots and Decepticons - do battle in yet another whiz-bang-blur of an action sequence soundtracked by headache-inducing dubstep.


And yes, it's also there with the film's blatant product placements and tie-ins, this time not-so-subtely advertising everything from hip-hop stereo systems to energy drinks and - yep - even women's lingerie.

Age of Extinction smugly knows it's going to be among the year's biggest blockbusters, so it doesn't mess with its formula of hunks, babes, cars and droids strictly employed since the 2007 original.

That's despite this being billed as somewhat of a reboot, with muscle-bound lunkhead Mark Wahlberg replacing the fast-talking antics of Shia LaBeouf in the three previous instalments.

This one also comes with a cast straight out of a sun-drenched Coke commercial, with Irish lad Jack Reynor for the girls, and impossibly long-limbed Nicola Peltz for the guys.

But, despite it's box-ticking obviousness, its blatant ripping off of its predecessors, its terrible one-liners and obvious jibes at itself, this is a grubby guilty pleasure that can be enjoyed on a purely visceral level.

Sure, you'll have to get over some stuff. Like believing that Mark Wahlberg is actually some kind of mad, undiscovered inventor genius, who actually has the skills to repair a trashed truck that might just be the long lost Optimus Prime.

Or that governments really would want to use alien metal to clone Transformers and create their own armies - especially after the city-destroying events of the previous film. It's hard to see Obama approving that one.

That it all ends up going horribly wrong in a 40-minute set piece in China is a somewhat muted commentary on corporate America, and a predictable and jarring mashup between Robocop and Jurassic Park that has to be seen to be believed. Or not, if you have indeed had enough at the two-hour mark.

This one comes with several new bots - most notably the sleek silver Galvatron and bullying menace Lockdown. They're aided by some deliciously dark baddies courtesy of Frasier's Kelsey Grammer doing his bad Boss-thing as a government official, and scene-stealing tough guy Titus Welliver as the head of a team of secret agents tracking and destroying the last remaining Autobots.

But mostly what this Transformers does is exactly what previous instalments do: bash you about with heavy metal machinery so often you'll need an ice pack and a lie-down afterwards.

Transformers: Age of Extinction
Director: Michael Bay
Starring: Mark Wahlberg, Stanley Tucci
Rating: M
Stars: Three
Running time: 165 minutes
Verdict: These robots tick all the boxes