Greenberg 

Remember that great John Lennon lyric: “Life is what happens to you while you’re busy making other plans"? It could serve nicely as the tagline for writer-director Noah Baumbach’s latest wryly comic study of disappointment, the story of an angry young man who’s grown into an angry middle-aged man without having made up his mind whether he’s madder at the world or himself.

To play the eponymous crank, Ben Stiller appears to have steeped himself in the filmmaker’s previous work. I challenge anyone familiar with The Squid and the Whale to watch this meticulously calibrated performance and tell me the actor’s not channeling the peevish character played by Chris Messina) is away on a six-week vacation in Vietnam, and Greenberg has agreed to housesit his fabulous hillside Hollywood crib. One senses that, in the back of his conflicted mind, it represents a homecoming to the sort of home that should have been his.

Greenberg is not a people person. Where he once wrote songs, he now spends his vast supply of unstructured time composing nitpicky letters of complaint to everyone from the heads of Starbucks and American Airlines to Mayor Bloomberg, and glaring out the window at the happy neighbors who’ve been given permission to avail themselves of the place’s Olympic-size pool. Two human beings do become featured players in the mouthy misanthrope’s private drama, however: One is a former bandmate. The other is his brother’s obliging, 25-year-old personal assistant.

Mumblecore veteran Greta Gerwig plays Florence, a sweet, somewhat befuddled but well-intentioned soul more accustomed to walking the dog than being treated like one. The relationship that evolves between her and Greenberg vacillates between botched attempts at intimacy and outright psychological abuse. Is she a glutton for punishment, or does she have reason to suspect he’s not entirely the jerk he seems? Theirs may be the most dysfunctional romance in screen history. I guarantee that they share the most awkward sex scene ever committed to film.

The true heart of the movie, though, is the weathered friendship between Greenberg and a former bandmate named Ivan, affectingly rendered by Rhys Ifans. They share one of the scenes for which the movie is likely to be remembered, a meditation on the aging process set in L.A. landmark Musso & Frank. Ivan observes, “Youth is wasted on the young.” Greenberg snaps, “I’d go further. I’d go, ‘Life is wasted on ... people.’”

The thing is, while Stiller’s character truly believes his life has been wasted, Ifans’ has done the work required to embrace “the life you never planned on.” In his case, that means beating drugs and the bottle, becoming a father, and holding his marriage together. He’s done something else his friend has never managed to do: forgive him.

With his last few films, Baumbach has established himself as the cinema’s poet laureate of the pretentious and self-obsessed. He’s unrivaled in the creation of articulate narcissists who, despite their IQs and gifts, are incapable of seeing past their own egos, and Greenberg is his most daring work in this vein to date. The filmmaker dares to make a movie about a thoroughly unlikable human being and then dares us not to care about him.