PARK CITY - Around halfway through "Don Jon's Addiction," a mildly amusing and more-than-mildly smarmy directorial debut from Joseph Gordon-Levitt, protagonist Jon (Gordon-Levitt himself) takes his newly acquired girlfriend Barbara (Scarlett Johansson) out to the movies. The film is her choice: a fictitious but unmistakably insipid-looking romantic comedy titled "Special Someone," starring Anne Hathaway and Channing Tatum. (Well, their faces, if not their names.) As the movie-within-a-movie ends with the couple driving into the sunset, wedding veil flapping in the breeze, Jon rolls his eyes while Barbara coos with pleasure. Walking out of the cinema, she dimly wonders aloud why real life can't replicate this marshmallow fantasy.

The irony is twofold, though I sense Gordon-Levitt only intended one of those folds: the fact that, for all his sneering, Jon has been severely addicted to online pornography since adolescence, and is therefore no less susceptible than his girlfriend to the allure of fantasy. It's debatable, however, whether "Don Jon's Addiction" is in a position to be parsing such subtleties at all, given that it's finally no less heightened a romantic fantasy than the date movie it's mocking.

At more than one point in "Don Jon's Addiction," it occurred to me that I'd actually rather be watching "Special Someone" -- if only to get away from curiously loathsome character the routinely likeable Gordon-Levitt has selflessly penned for himself, and around which he has not-so-selflessly constructed the entire film.

A working-class New Jersey lothario with gym-built shoulders and gel-built hair, Jon Martello -- nicknamed The Don by his equally loutish friends, hence the title's apposite "Don Juan" bastardization -- is not, to be fair, a character we're much supposed to like. Aside from his questionable personal style and his 10-a-day masturbation habit, the man is a beyond-the-pale misogynist, sizing up women like sides of meat at his local club, and reacting with surly bemusement when one over the age of 40 (Julianne Moore) dares to approach him at the evening class they share. (Well, at least he's committed to some measure of self-improvement.)

Redemption is on the cards, and it amounts to a two-step program: ditch the porn and find a nice girl, not necessarily in that order. Jon freely admits that he's unable to enjoy sexual intercourse as much as he enjoys porn, and the film's not-unreasonable argument is that he's one of a generation of men whose ready access to hard-core material from an early age has given them unmatchable expectations of sex itself.

There's a strong film -- and not necessarily a heavy one -- to be made on this phenomenon, but "Don Jon's Addiction" can't find quite the appropriate comic tone, ultimately settling on a laddish archness that undermines the seriousness of the addiction in question. It's unclear, for example, how complicit the script is in Jon's irritation that Barbara ditches him when he proves unable to kick the habit, particularly when his every whack-off session is rapidly cut to zingy comic effect.

Of course, any closer scrutiny of his problem would disrupt the fantasy that eventually allows Jon to meet cute with the far smarter, more mature specimen played by Moore -- who provides the film with whatever warmth and empathy it possesses. Unsurprisingly, not a hint offered as to why she keeps pursuing him. Any closer scrutiny would sit awkwardly with Gordon-Levitt's sitcom-style takedown of New Jersey society, complete with a wifebeater-clad Tony Danza as Jon's horndog dad and SNL-level Joisey accents across the ensemble. (Johansson, seemingly called upon to do an impression of Adriana La Cerva, does it with some gusto, though the film never rewards her effort with anything approaching a character.)

Speaking of which, any closer scrutiny would require "Don Jon's Addiction" to create an actual character for himself as well as others: it's hard to root for Jon's rehabilitation when it's so hard to see the person his addiction is preventing him from being -- by the end, he's been persuaded to use less product in his hair, which is a step in the right direction, but something's missing from this character arc. The film is assembled with some pep and performed with some vigor; Gordon-Levitt, funnily enough, has the directorial snap to make a cute little romcom. But there's little here to care for or about: what promises to be a friskier version of "Shame" winds up closer to a Very Special Episode of "Jersey Shore."

Guy Lodge is a South African-born critic and sometime screenwriter. In addition to his work at In Contention, he is a freelance contributor to Variety, Time Out, Empire and The Guardian. He lives well beyond his means in London.