Did anyone expect Michael Bay not to take the bigger, more, louder approach with a sequel to 2007's Transformers.

By now tidbits (like the original containing only a handful of Transformers while this film contains over 40 and the number of terabytes and computers necessary for Industrial Light and Magic to render a frame) are entering the film's zeitgeist, but what it also means is that both Bay himself and ILM look to have stretched themselves a little thin.

It might have just been the inventiveness of the first film where the computer generated robots and the real world looked so seamless, but this time they look slightly cartoonier and rushed, the textures and lighting not quite matching. Of course, there are far more outdoor scenes with far more robots, so it might just be an age-old problem at ILM – the Imperial Walker battle on Hoth in The Empire Strikes Back was much more difficult to rig even in the late 1970s because the bright ambient lighting of the snowy background showed up the flaws in the process. The same might apply to the CGI in Revenge of the Fallen, as an early scene of a huge, two-wheeled beast attacking Shanghai looks far more realistic.

The film might also suffer from plain old sequel blues, the idea fresh and exciting before, enough to hook you in because you'd never seen it before. But there was also a disconnect between two moods in the original, albeit a slight one but much more pronounced in Revenge of the Fallen. One on hand you have what Bay does best – professional soldiers who talk the talk surrounded by cool, real-world military hardware preparing for war, and on the other you have giant alien robots stomping around far off planets spouting cartoonish profundities like 'revenge will be mine'.

It's a serious military thriller posting as a cartoon, or vice versa, and this time the gulf between the two just makes the whole thing look silly. Add to that a mostly asinine, PG script, some outright stupid characters like the bickering twin bots Mudflap and Skids and comedy that goes too far (like Sam's ditzy mother eating hash cookies) and the whole thing feels slightly silly. Where the original film had some comic touches that didn't want to overstay their welcome, Fallen is (if there is such a thing) too funny.

That said, Bay is still at the top of his particular game, with cameras whooshing theatrically through a scene and the many metallic scrapes still exhilarating to watch. He's one of the few directors completely unafraid to go big – when you realise a bunch of Decepticon digging implements in the Egyptian desert are going to transform and attack he goes you one better, the circus tent-sized Devastator building itself by attaching them all together. His music video visuals make for a frenetic experience that's everything you expect both from him and the subject matter.

The plot is a throwaway concern featuring another Macguffin that everybody wants to find. An opening coda explains how the descendants of the Autobots and Decepticons have been on Earth for millennia, hidden among us after having built a huge machine designed to destroy the sun for their power source (no, it makes no sense to us either).

With Megatron resurrected thanks to a piece of the all-spark found in Sam's jacket from the first film, he can finish his life's work – destroying the last Prime alive (Optimus) and bringing his master, a Decepticon named The Fallen, to Earth to find and start the sun-destroying machine. The entire point of the story is actually laid out in a five minute sequence of exposition thanks to a redeemed Decepticon telling the gang what they're up against.

Fighting together in a secret alliance after the events of the first movie, the military and Autobots have to find and destroy the machine before the Decepticons can activate it, and Sam (LeBeouf) and Mikaela (Fox) are dragged back into the fight to find another plot device to bring back an old friend.

Shia LeBeouf does his best teenage Woody Allen, making you wonder when he'll want to use his Hollywood clout to flex his dramatic muscles, and Megan Fox is a Hot Chicks and Motorcycles calendar that speaks. After telling a reporter 'it's too easy to sell your sexuality' while promoting the first film in 2007, one wonders what she's using here as she lolls over a motorcycle in cut off denim shorts or strips off a leather riding suit to reveal the babydoll top underneath, a full mouth of lipstick even while running through Egyptian ruins.

Though Revenge of the Fallen looks mostly great it might suffer from Star Wars Episode 1: The Phantom Menace syndrome. The problem lies less with any faults inherent in the original movie than in our collective memory of it being better than it really was. Being Michael Bay, he'd hardly improve upon it using Shakespearian drama or gritty, kitchen-sink realism, but by even more giant robots kicking seven shades of crap out of each other.