Oddly intellectual comedy with SoHo New York vibes. While We’re Young is a mild name for a movie but a big entry for Noah Baumbach whose “The Squid and the Whale” (2005) is one of the unassuming masterpieces of this century and “Greenberg” (2010) a character study that defied convention. Ben Stiller and Naomi Watts play a childless mid-forties married couple who feel their friends with babies are straying from them. Stiller is an over-finicky documentary filmmaker who has been working ten years on one film, and his wife and peers around him believe he fears success. He goes through a big life change when he meets a young filmmaker (Adam Driver as Jamie, Amanda Seyfried as his bohemian wife) who has the chutzpah to frankly get things done.

This is a very funny movie about the generation gap divide, and also has brainier humor about the technology age of iPhones and Twitter that is way past, I dunno, this year’s Best Screenplay winner “Birdman.” There is a moment that has to be seen to be appreciated, when three adults are playing with their cell phones and the other comments how this is socially accepted now, like the turning point when1800’s women began to show ankle in public. This isn’t truly hilarious until you’ve seen how Baumbach sets up the joke.

Stiller wears a hipster hat to feel young, Watts takes hip-hop classes with moves befitting to her and no one else in class. Now a mentor, he takes the young filmmaker Jamie out to lunch and dinners, listens to his pitches and joins him at parties. You would think this would be one of those comedies where the old guy lives young until exhaustion leads him back to his old life.

Wrong. “While We’re Young” is very much like a 1980’s peak Woody Allen film like “Crimes and Misdemeanors” that looks mercilessly at the implosion of its protagonist. Stiller can play the mainstream doofus better than anyone in Hollywood, but on occasion like in Baumbach’s “Greenberg” or in an inconsolable misfire like 2004’s “Envy,” he can play a very dark guy who can’t stand the idea of someone else around him succeeding beyond his level.

Here’s a portrait of a small ego man who wants to cripple the success of his protégé (how dare that social climber!), who speaks disrespectfully to his father-in-law, and tells his wife to “f***-off, in a non-ironic way, really, f***-off!” I was often uncertain where Baumbach was going with this, but that’s part of his non-commercial, anything can happen appeal. Baumbach complicates us by how he gets us to like Watts, Driver, Seyfried and Charles Grodin (as the father-in-law who happens to be an honored documentary filmmaker) all the while we watch in contrast Stiller’s descent. To alleviate his angst he wants more than ever to have a child.

Stiller has confessed he has trouble with bipolar manic depression in real life, and has undergone therapy for it. He seems to bring his knowledge to the subject anytime he works with Baumbach.

Note: I know the commercial ads are pressing this as a light, frivolous affair. But Baumbach’s film is more like a vintage Woody Allen serio-comedy. Only more scintillating.

96 Minutes. Rated R.

DRAMA / FOOD FOR THOUGHT / PROVOCATIVE MOOD 

Film Cousins: “I Love You, Alice B. Toklas!” (1968); “Husbands and Wives” (1992); “Greenberg” (2010); “Young Adult” (2011).