Joseph Gordon-Levitt's debut as a triple threat—writer, director and star, a la Clint Eastwood—is appropriately festooned with the time-honored totems of macho masculinity. We've got cartoonish muscles, unbridled rage, some good old-fashioned misogyny and, of course, sex that's all about the man.

"Condoms are just terrible," whines Jon (Gordon-Levitt), a Guido beefcake who likes porn better than real sex. "But you gotta wear one because, unlike porn, real pussy will kill you."

Or rather, real pussy—with all its trappings of commitment—will kill your bachelor lifestyle. Jon doesn't have time for that. He's too busy clubbing with his sleazy pals, racking up one-night stands, jerking off, and then grunting out obligatory repentance prayers during bench presses and pull-ups at the gym. He is so immersed in Internet porn that it's hard to tell whether his attitudes about sex and love are the product or the cause of his obsession.

When Jon meets super-fox Barbara (Scarlett Johansson) and actually tries to date her, he realizes that his love for porn may not be as normal as he thinks. Barbara, a rich control freak who constantly chews gum with her mouth open and twirls her hair with clawlike fingernails, freaks out after snooping into Jon's browser history and discovering that he's visited 42 porn sites in one day. Her abject horror at his obsessive meat-pounding kicks off the slow unraveling of Jon's belief in porn as the apex of sexual stimulation.

The character of Jon is a total departure from Gordon-Levitt's charming, shy-guy roles, and one that he absolutely nails. Granted, it's far and away the least attractive he's ever been, proving that Guido style has the power to reduce even the dreamiest of dudes to a greasy orange shell of their former selves. But Gordon-Levitt brings just enough depth to the character, and to the film overall, to turn a schlocky premise into an honest and approachable exploration of how porn—and really, any other addictive simulation of reality—can cheat us out of the richness of actual experiences. And somehow, putting that high-level concept through the lens of a slimy meathead makes something rather complicated seem very, very simple. The main character may wear skintight deep V's and jizz in his pants on a regular basis, but the message behind Don Jon remains subtly brilliant.

Critic's Grade: A-

SEE IT: Don Jon is rated R. It opens Friday at Cedar Hills, Eastport, Clackamas, Living Room, Bridgeport, Lloyd Center, Division.