If there were a literate adult in the western world who knew next to nothing about modern-day American film-making it would probably take them a few hours at most to discover Michael Bay is (still) the discerning cineaste's whipping-boy of choice. And yet few people seem too eager to consider whether or not such widespread derision might be a [b]bad[/b] thing. Even in the age of the new internet optimism it's practically set in stone that the 44-year-old director has given the world nothing beyond a string of terrible, terrible movies where things explode and anyone who enjoys them ought to refrain from displaying their appreciation until they're behind closed doors and away from polite company. Should anyone find fault with Paul Greengrass or Christopher Nolan's handling of frenetic hand-to-hand set-pieces their fans will laugh the offending critic out of the room, yet at the same time the same people have no problem with laying into Michael Bay's love of hyper-kinetic action and rapid-fire jump-cutting.

Partly this has to be down to its being near impossible to argue the man's detractors don't have a case against him. It's difficult to deny Bay represents the worst tendencies of modern-day American film-making, something which sounds perfectly convincing to anyone after, say, half an hour with any of his back catalogue – excess for the sake of excess and a near total lack of structure, subtlety, restraint or narrative coherence. He scorns his critics' opinions, blissfully unconcerned with what anyone thinks of him beyond his legions of adoring devotees.

Barely fifteen minutes in, [i]Transformers: Revenge of the Fallen[/i] doesn't seem likely to bring the man many new converts, or make defending him any easier. Making a sequel for the fans is one thing, yet [i]Revenge of the Fallen[/i] opens astonishingly lazily by anyone's standards. A perfunctory voiceover by way of an introduction, some brief glimpses of one or two of the supporting cast from the original, and then Bay opens the throttle, leaving anyone new to the franchise in the dust. The [b]good[/b] robots are hunting down the [b]bad[/b] robots with the aid of a small contingent of human special operatives whose main role seems to be to die in almost farcical displays of pointless heroism. Steve Jablonsky's score thunders into action. The camera contorts wildly around hundreds of man-hours worth of ILM's work tearing across the screen. People shout incoherent military jargon. Things explode. It seems not unlike a convenient shopping list of reasons to walk out of the theatre in disgust.

Then Optimus Prime actually appears on screen and abruptly the viewer's inner child is jolted wide awake. The heroes' leader rolls out of an American military transport in vehicle form, transforms to humanoid guise on the way down, deploys multiple parachutes to slow his descent and then changes back into a Peterbilt just before hitting the road – it's over in minutes but this fairly ludicrous conceit is executed with such obvious glee it's enough to remind anyone why they came back for more after the first film.

Not that anyone would return for the plot, such as it is. A piece fell off the original macguffin, dire warnings foreshadow evil robot leader Megatron's return from a watery grave to claim said piece and hijinks ensue. Roberto Orci, Alex Kurtzman and Ehren Kruger's script attempts to flesh out the franchise's lore with further nods to the original cartoon, but the trio seem well aware their target audience are largely concerned neither with this nor the ongoing subplot about Shia LaBeouf's Sam Witwicky and his attempts to balance saving the world and going to college.

Yet for all the mechanical efficiency on display it's hard to shake the impression that [b]Bay[/b] cares, much as he directed even the most embarrassing missteps in the first [i]Transformers[/i] with the same boyish enthusiasm he showed for everything else up to the final, dizzying set-piece. A early reminder soon after the opening pyrotechnics that the macguffin has the power to bring inert mechanical objects to life is another excuse to blow things up, true – half the Witwicky family home in this case. It's also a captivating display of artistic invention and a genuinely funny poke at the idiocies of much of the backstory thus far. [i]Revenge of the Fallen[/i] doesn't preclude the inevitable [i]Simpsons[/i] episode satirising the film, but at times it manages a fair stab at sending itself up.

The main issue, though, is simply that Bay seems unable to maintain this form for much longer than he prefers to hold a camera in place. Too much of his caring feels like the guileless invitation of a child who just wants someone to come and see what they've done, with praise almost an afterthought. As a result, for every high point there's a maddening low which almost begs to be savaged. The lengthy fight scene on the edge of a forest (the one that graces the trailer) is astonishing, Optimus Prime defending Shia LaBeouf from multiple enemies, Bay's camera skipping effortlessly from point-blank to bird's eye views – not to mention the writers appear to have realised no-one cares what sort of gruesome carnage they visit on the robot cast. The results are frequently shocking; what other summer blockbuster shows a fight where the victor tears the loser's head in half with his bare hands? Yet weirdly this rarely feels like part of the problem; far more pressing is how (relatively) lengthy sequences concentrate on multiple CG protagonists sporting identical colour schemes, with designs incorporating painfully similar geometric forms, and nothing done to help the audience pick one out from the other.

And it goes on. We have an elderly Transformer – yes, you read that right – where Michael Bay somehow manages to invest the character with a degree of warmth, dignity and gravitas. Then he follows this with fart jokes. For every gag that hits the mark, he insists on running the next into the ground; if anyone missed Bay's trademark fetish for small, ugly, over-sexed canines by the halfway point he's evidently determined they [b]will[/b] catch on by the end of the film. The camera's lingering on a scantily-clad Megan Fox persistently undermines any attempt she makes to act, even before the introduction of what is quite possibly the most ludicrous femme fatale in the history of the medium. Shia LaBeouf orders Mr & Mrs Witwicky to head for safety before the climactic showdown and Bay, astonishingly, turns this into a fairly effective Big Moment – yet the earlier routine where Sam's parents visit his new dorm (there are cookies with a secret ingredient) has to rank as one of the most cringingly awful attempts at comedy ever seen outside of a Rob Schneider vehicle. [i]Revenge of the Fallen[/i] is a mess.

But it can be fun watching a child turned loose on the biggest sandpit in the world. Anyone (other than Bay and his armies of the faithful) would struggle to call the [i]Transformers[/i] sequel a [b]good[/b] film, but for those who can stay focused throughout its mammoth two-and-a-half-hour running time it's a more than enjoyable experience. It's frustrating thinking of the movie it [b]could[/b] have been if Michael Bay could sit still for more than thirty seconds at a time; if someone would suggest to him not all jokes bear shouting out to everyone in earshot; if twenty minutes or more could have been left in the editing suite...

And then the climax rolls around and Bay drags together multiple viewpoints with slick, practised expertise, reminding us that even when scrappy, lazy, greedy or flagrantly egotistical, few other directors make big-screen escapism feel so gloriously, thrillingly indulgent. [b]That[/b] theme kicks in. The human contingent actually make a difference, grunts as well as top billing, to the point the viewer even ends up emotionally invested in the endless parade of redshirts. The pyrotechnics elicit a sense of shock and awe that actually works with the pacing to staggering effect. Camerawork and set-pieces both convey a sense of scale that dwarfs anything that came before the final half hour. Again, Bay actually finds time to dwell on a pivotal moment without hysterical emoting or overly literal dialogue for those who failed to 'get' the underlying themes. We care. We're willing to overlook the mess, the sensory overload, the none-too-subtle winks to the audience, the plot holes... even the robot testicles.

[i]Transformers: Revenge of the Fallen[/i] is neither a 'good' film, nor is it going to appeal to everyone, and many of those who walk out of the theatre happy will have forgotten it before the BluRay release hits the shelves. But it's hard for anyone with an open mind not to watch it and feel there's far more honest enjoyment to be had with Michael Bay and his box of glittering toys than there is in the company of any number of critically acclaimed directors. It's childish, certainly, but sometimes we forget how much fun it can really be to watch things explode.