Producers: Seth Rogen, Evan Goldberg and James Weaver   Director: Jeff Rowe and Kyler Spears   Screenplay: Seth Rogen, Evan Goldberg, Jeff Rowe, Dan Hernandez and Benji Samit   Cast: Micah Abbey, Shamon Brown Jr., Nicolas Cantu, Brady Noon, Ice Cube, Ayo Edebiri, Jackie Chan, Hannibal Buress, Rose Byrne, John Cena, Natasia Demetriou, Giancarlo Espositio, Post Malone, Seth Rogen, Paul Rudd and Maya Rudolph   Distributor: Paramount Pictures

Grade: B-

Given the dismal quality of the previous Teenage Mutant Ninja Turtles movies, it might seem the faintest of praise to say that “Mutant Mayhem” is the best of the lot.  But while the picture, co-written by Seth Rogen (who also produced, as well as voicing a mutant warthog called Bebop), is no great shakes in narrative terms, overall it has a jovial (if juvenile) vibe and a look that’s distinctive, if not exactly attractive.  Though it will appeal primarily to nostalgia buffs who grew up on the many past incarnations of the goofy heroes in a half shell, who have been around for some four decades in various formats, even non-devotees might find it at least tolerable.

The two Spider-Man multiverse movies proved that animation that avoided the cookie-cutter CGI style so prevalent nowadays could be a major plus, and “Mayhem” offers grungy, indie comic images and characters that resemble unfinished Claymation figures.  (Yashar Kassai was the production designer.)  It takes a while to accustom yourself to the aesthetic, which initially seems rather ugly, but it grows on you, and by the close has become familiar enough not to be bothersome.

As to plot, Rogen and his collaborators present a pretty conventional origins story, though with a few tweaks that may antagonize some long-time fans but be taken in stride by most; this material is hardly a sacred scroll, after all.  The anthropomorphic turtles—Donatello (voiced by Micah Abbey), Michelangelo (Shamon Brown Jr.), Leonardo (Nicolas Cantu) and Raphael (Brady Noon)—resulted from experiments being done by mad scientist Baxter Stockman (Giancarlo Esposito) that were invaded by goons loyal to evil Cynthia Utrom (Maya Rudolph), who wants to use his research to fashion super soldiers.  Flushed into the sewer system, the four babes were rescued—as we’re told in a flashback related by their surrogate daddy and mentor, the intelligent rate Splinter (Jackie Chan)—who trained them in martial arts and kept them hidden in the sewers, away from evil humans.

But the quartet are now fifteen, and anxious to see the world.  During an unauthorized outing they encounter April O’Neil (Ayo Edebiri), a high-school outcast who wants to be an investigative reporter, and help her regain her motorcycle, stolen by a biker gang.  After she overcomes her initial shock, they agree to work together to catch Super Fly (Ice Cube), a mutant insect, also the result of Stockman’s lab, who, along with his band of other mutant critters—a frog (Hannibal Buress), an alligator (Rose Byrne), a rhino (John Cena), a manta ray (Post Malone), a bat (Natasia Demetriou), a gecko (Paul Rudd) and Rogen’s Bebop—as well as human hirelings, is stealing electronics to construct a machine that will use Stockman’s ooze to destroy humankind.  And in the background Utrom is trying to capture the turtles to use their blood for her unholy project.

Despite the weirdness innate to the leads, the screenplay doesn’t really vary overmuch from the usual superhero template, though one can rejoice in its avoidance to today’s most overused cliché, a multiverse (sorry, Spidey).  And all the convolutions and changes of heart still lead up a protracted battle with a Godzilla-sized Super Fly in the streets of the great metropolis.  The message of tolerance and acceptance of “the other” is standard-issue stuff, too, as is the preparation for sequel possibilities inherent in the Utrom subplot, with Rudolph’s mushy-mouthed accent checking one’s hopefulness about a continuation.  And the pop favorites plugged into the competent but unexceptional score by Trent Reznor and Atticus Ross are rather on-the-nose.

But there’s an adolescent glee to the banter among the turtles, nicely voiced by actual teens, and to the discrepancy between the vision of high school they’ve learned from Ferris Bueller and the actual thing April, genially brought to life by Edebiri, has to put up with.  Chan’s tongue-in-cheek serious take on Splinter is an added bonus, while Ice Cube and all the starry supporting folk playing his mutant minions overdoing things with gusto.  There are, of course, elements in all this that pass from juvenile to puerile, like O’Neil’s nickname derived from her nervous inability to appear on camera without throwing up prodigiously.  Projectile vomiting has become a commonplace in so-called family movies nowadays, but it’s certainly one best resisted.

Overall, the pluses outweigh the minuses in “Mutant Mayhem,” which is obviously intended as a start to a new series allowing fans to watch the four Renaissance painter-named dudes grow up.  If it does in fact result in a further extension of an already crowded franchise, one can only hope future installments will maintain its virtues while excising some of the flaws.