It would be a grievous understatement to call Matthew Vaughn’s adaptation of Mark Millar and John S. Romita, Jr.’s Marvel series one of the best comic book movies ever made. It is, but more importantly “Kick-Ass” is simply a hugely entertaining picture irrespective of its origin, a crazily inspired mixture of teen humor and flamboyant action that’s like a melange of Judd Apatow, Sam Raimi, John Woo and Vaughn’s old partner, Guy Ritchie. If you can stomach the violence—cartoonish but still abrasive—you’ll find it giddy fun and almost shamefully enjoyable.

The central figure is high schooler Dave Lizewski (Aaron Johnson), who’s infatuated with unattainable campus beauty Katie (Lyndsy Fonseca) and, with his nerdy pals Marty (Clark Duke) and Todd (Evan Peters), addicted to comic books. Dave innocently wonders one day why nobody’s actually tried to become a Batman-like hero, intervening to prevent crime, and decides to try it himself. Ordering a green-and-yellow scuba suit on-line, he dons the outfit and goes off to do good. His first encounter with some neighborhood thugs (and a speeding car) sends him to the hospital. But it doesn’t make him quit, and onlookers who use their phones to record his exploits—even when he’s getting thrashed—make him an instant internet celebrity as Kick-Ass.

Among those watching are far more developed vigilantes, ex-cop (and ex-con) Damon (Nicolas Cage) and his young daughter Mindy (Chloe Grace Moretz), who moonlight as the costumed duo Big Daddy and Hit-Girl. Their goal is to cripple the operation of crime lord Frank D’Amico (Mark Strong), whom Damon blames for the death of his wife and his own incarceration. They come into contact with Kick-Ass by saving him when he confronts a member of D’Amico’s gang who’s been threatening Katie, who by then has befriended Dave after she concludes that he’s gay—and therefore great BFF confidante material.

Matters escalate when D’Amico, believing that Kick-Ass is the source of his problems, accepts a suggestion of his wannabe mobster son Chris (Christopher Mintz-Plasse) that he should take on a masked persona of his own, Red Mist, connect with Kick-Ass, and betray him to his dad. But the ruse instead reveals the existence of Big Daddy and Hit-Girl and sets up a pretty nasty third act in which D’Amico’s minions take aim at all the heroes and those who survive, in turn, go after him and his gang big-time.

One might not expect the picture’s combination of teenage goofball humor, some of which gets rather gross, and vigilante violence, some of which gets pretty gruesome (especially in the final confrontation between Frank and Hit-Girl), to be palatable. And it’s undoubtedly true that some viewers will find, in particular, the idea of a ten-year old girl methodically dispatching grown men with all sorts of kicks, punches, firearms and sharp implements in poor taste. But the high school stuff is surprisingly engaging—the movie even makes Katie’s assumption that Dave is gay, and his failure to disabuse her of the notion in order to stay close to her, appealing rather than unsettling. And though the fights aren’t always staged with the degree of stylization one might desire—the screen is necessarily a more “realistic” realm than the printed page, after all, and what requires a reader’s imagination in a book (even an illustrated one) becomes more explicit and brutal when rendered on film, unless it’s done with the utmost care—they only occasionally go over the line.

And if one accepts the movie for what it is—not only a wildly over-the-top distillation of the comic book ethos but also a subtly acute commentary on the fanaticism that can result from it—you’ll appreciate what Vaughn has managed here. His technique is no less assured than it was in his over-praised debut “Layer Cake,” but it’s not so ostentatiously clever (though it has its share of zippy moments—like the quick flashback that recounts how Dave’s mother died, not as perfect as Nabokov’s “picnic, lightning” but in the same class). And the visuals (from production designer Russell De Rozario, art director John King, and set decorator Tina Jones) are set off nicely by Ben Davis’ smooth but not ultra-slick cinematography. Equally praiseworthy are the sharp editing by Jon Harris, Pietro Scalia and Eddie Hamilton, the mix of music by John Murphy, Henry Jackman, Marius De Vries and Ilan Eshkeri (with supervision by Ian Neil), the costumes by Sammy Sheldon (especially the ludicrous super-hero outfits), and the effects (which include a montage of comic panels to swiftly sketch Damon’s past).

Vaughn has also cast the picture beautifully. Johnson makes an amiably gawky, earnest hero, Cage puts his gift for oddball poses and line readings to excellent use as the daft but dedicated Damon, and Mintz-Plasse brings an undercurrent of real menace to the snarky Chris D’Amico. Strong, Duke, Peters and Fonseca are all spot-on. But things would still fall apart if it weren’t for Moretz, who somehow manages to make Mindy’s mix of adolescent spunk, girlish vulnerability and super-martial arts dexterity plausible within the admittedly far-fetched context.

The fact that, as refashioned by Vaughn and Jane Goldman, “Kick-Ass” makes a few changes to Millar and Romita’s narrative may disturb some fanboys. But what’s far more important is not just the picture’s general fidelity to the source, but its ability to channel its spirit. Unlike a picture such as “Watchmen,” which tried but failed to do that, this one succeeds beyond one’s wildest expectations.