'Don Jon' is funnier than you expect, smarter than it looks and more touching/sincere than anticipated.
In short: 'Don Jon' (Joseph Gordon-Levitt) objectifies everything in his life, especially women. When he meets a girl who might be 'the one' (Scarlett Johansson), Jon must face his porn addiction and acknowledge why he pursues his philandering lifestyle. (watch the trailer)
Reducing Gordon-Levitt's triple-threat (acting/directing/writing) debut as a simply a 'movie about masturbating' is silly. This is an ambitious and layered film that's part character study of an addict and part critique of a fantasy-obsessed culture.
But first and foremost, 'Don Jon' is a sharp and hilarious comedy. At its core, this is a film about an addict whose addiction has eroded his overall satisfaction with life. If the addiction were heroin or booze, this film would have a much darker tone. But JGL turns the addiction drama on its head, fills it with fun characters and packs its screenplay with great comedic beats/hilarious dialogue - all without compromising the story's addiction-based narrative.
JGL also prove he has a masterful control of story conventions. Some basic elements of 'Don Jon' are repeated over and over again - Jon confessing his sins at church, working out at the gym, eating Sunday dinner with his family. Although these elements are repeated, they are slightly different each time - and they reveal Jon's evolution throughout the film.
Perfect example: Gordon-Levitt even turns the simple start-up sound of a MacBook into a hilarious comedic device.
Finally - and perhaps most importantly - Joseph Gordon-Levitt has directed a film with a clear, signature voice. It's funny tone never takes away from its honest moments. Its critique of a society that objectifies almost everything isn't so cynical as to jarringly contrast with the film's oddly touching, emotional core.
However, since no film is perfect, 'Don Jon' isn't without its flaws. The main actresses seem to be acting in two very different movies: Scarlett Johansson dangerously flirts with playing a character from an 'SNL' skit while Julianne Moore gives a wonderful - but more grounded - dramatic performance. Although the ending is touching and makes sense - it's also very abrupt. And in its effort to critique a culture of objectification, 'Don Jon' itself would fail the 'Bechdel Test' miserably.
Final word: 'Don Jon' is an excellent triple-threat debut for Gordon-Levitt, who has crafted an interesting comedy with an unexpected depth.