The title may be “Transformers,” but “Dark of the Moon,” the third installment of the Michael Bay franchise based on the Hasbro action figures, is just more of the same—except for the subtraction of Megan Fox and the addition of 3D, which hardly seems a fair swap, although to be fair Bay has added a Fox substitute in Rosie Huntington-Whiteley, a tall, svelte, blonde British model who’s unaccountably become the new girlfriend of brash but supposedly lovable series hero Sam Witwicky (Shia LaBeouf).

Witwicky, now an unemployed college grad looking for work, he gets a job (unfortunately sans pay) without even applying for it—once again fighting the evil Decepticons in concert with his old pals, the good Autobots led by Optimus Prime (voiced by Peter Cullen). He’s drawn into this latest (and one hopes final) chapter in the endless war between the opposing armies of clunking aliens when the long-unnoticed wreckage of an Autobot ship is discovered on the far side of the moon and investigated by the Apollo 11 mission.

This is the second summer sci-fi behemoth—following the “X-Men: First Class” revisionism on the Cuban Missile Crisis—that rewrite American history to suit its purposes. Here President Kennedy’s call for the manned moon landing is presented merely as a pretext to beat the Russkis to the craft and check it out stealthily. The fifty-year-old find become the basis for contemporary conflict when Optimus Prime learns of the vessel’s presence and rescues his predecessor and mentor Sentinel Prime (Leonard Nimoy) from his long dormancy in it. Unfortunately, that acts as the catalyst for the evil Decepticon leader Megatron (Hugo Weaving) to launch his plan to destroy the Autobots and enslave humanity—in which he has a new henchman, the snakelike Shockwave (Frank Welker).

The contortions of Magatron’s scheme are so silly that there’s little point in trying to unravel them. Suffice it to say that, after a stop in Washington to destroy a national moment (a requirement in all pictures like this since “Independence Day”—in this instance it’s the Lincoln Memorial), it al winds up with the Decepticons in control of a devastated Chicago as ground zero of Megatron’s hostile takeover of the planet, and Sam and his comrades-in-arms, both the Autobots and humans Captain Lennox (Josh Duhamel) and ex-Sergeant Epps (Tyrese Gibson), inside the city attempting to derail the plot. It’s personal for Sam, too, since his girlfriend Carly (Huntington-Whiteley) is trapped in a Windy City skyscraper with her slimy boss Dylan (Patrick Dempsey).

“Dark of the Moon,” like its predecessors the original “Transformers” (2007) and the sequel “Revenge of the Fallen” (2009), is a special-effects extravaganza, especially in the battle of Chicago that makes up the final forty minutes or so (though even those of us who know the city well will have trouble deciphering the topography of the conflict with any precision). But the constant use of CGI gets decidedly tiresome over the long haul (and this one is way too long, once again droning on for more than two-and-a-half hours). That big concluding battle is pretty much a visual mess (as are, oddly, the sequences juxtaposing real footage and staged scenes involving Presidents Kennedy and Obama). And it’s oddly dull as well, even when people are scrambling down the glass sides of skyscrapers that are tumbling to the ground.

That’s partially because the picture isn’t just poorly written, with streams of cliché that one can only hope are intended as send-ups of wretched dialogue, but also badly shot and edited. Amir Mokri’s camerawork relies far too much on rapid-fire movement and brutal close-ups, and the editing shared by Roger Barton, William Goldenberg and Joel Negron accentuates the jaggedness with its dizzying machine-gun style. Those qualities are part of the CGI sequences, too, which as a result are frequently indecipherable. And all the ‘bots remain dull metal-men—even the little ones that are Sam’s pets, and designed to be naughty gremlins, and the purportedly poignant Bumblebee.

With a few exceptions, the humans are no better. John Malkovich has some over-the-top fun as Sam’s supercilious boss, and John Turturro returns to chew up the scenery again as ex-man-in-black Simmon, as also do Kevin Dunn and Julie White as Sam’s sitcomish, intensely irritating parents. But though Huntington-Whiteley looks great running around in her designer dresses and ultra-tight jeans, her acting talent seems inferior even to Fox’s, which may explain some of the hyperkinetic editing in her scenes that seems designed to disguise her inadequacies in that department. Duhamel and Gibson strike the usual poses, and Dempsey is conventionally sleazy, while Frances McDormand is wasted as the purse-lipped director of the National Intelligence Agency, so-called. As for Ken Jeong, who’s stuck with the most deplorable material as an engineer named Wang, the less said the better; he’s an even more offensive stereotype than he was in the “Hangover” movies.

The central problem, though, is LaBeouf. In the first episode he was a likable schlub, but over the course of the series his character has developed into a loud, abrasive whiner, and in “Moon” he’s pretty much insufferable. It’s difficult to embrace an action-adventure movie when its hero is a guy it’s hard to root for.

“Dark of the Moon” is, in the end, a bombastic, elephantine bore whose lack of visceral excitement is topped only by its excess of stupidity. Like the later “Star Wars” episodes, though, it will probably be embraced nonetheless by die-hard fans, as well as by lemming-like sequel-goers who will traipse into theatres even for utter drek like the last two “Pirates of the Caribbean” movies. But it should really be consigned to the cinematic scrap heap.