(CNN) -- Noah Baumbach is emerging as an emotionally acute, not to say eviscerating, observer of the middle-class intelligentsia, the kind of people who write letters to "The New York Times" and might plausibly pop up in a Woody Allen movie.
Unlike the Woodman, Baumbach doesn't show his face on screen, but his films are no less personal for that: "The Squid and the Whale" was a sometimes wincingly autobiographical account of two boys torn between their divorcing parents, and he's not one to deflect an insight with a wisecrack. The cracks just cut deeper. I've rarely experienced an audience recoil from a character as passionately as they did to Nicole Kidman's toxically self-absorbed writer in "Margot at the Wedding" (maybe her best performance, incidentally). These are comedies in the sense that the characters are painfully ridiculous -- and all too recognizably real -- but Baumbach sure doesn't make it easy for himself, or us.
Roger Greenberg (Ben Stiller) is another neurotic narcissist, a middle-aged loner who comes back to Los Angeles to house-sit while his brother enjoys a long vacation in the Far East. Greenberg (only his brother calls him Roger) can feed the family dog, but the truth is that he desperately needs to regroup and recharge after a spell in a mental hospital.
He has one friend, Ivan (Rhys Ifans), who still has time for him and a wider circle of former friends who don't. We soon learn that Greenberg used to front a band, but it fell apart after he turned down a recording deal, and he's been in New York ever since, under-achieving on a permanent basis.
"I'm trying to do nothing for a while," is how he explains himself to anyone who will listen.
Stiller finds a note of defiance in this pathetic rationalization (along with his powerlessness, Greenberg has developed an angry streak), but it's clear to almost everyone how lost he really is. He's living in the past, fantasizing about his old girlfriend (a deftly ironic cameo by Baumbach's wife, Jennifer Jason Leigh) and scarcely able to look after himself, let alone his brother's dog.
It's hard to believe this hunched misanthrope grew up in sunny California -- he can barely doggy-paddle and always dresses for rain -- but Stiller knows him inside out. He shows us someone trapped in his own disappointment, flailing and failing.
Then there's Florence (Greta Gerwig), his brother's personal assistant/nanny, a wannabe singer who defaults to doormat status in almost any social exchange. Greenberg throws himself on her with an awkward mixture of condescension and vulnerability, and their fumbling relationship -- physical but scarcely intimate -- serves as a kind of love story, or at least the unspoken promise of one.
It's crucial to Baumbach's strategy that Gerwig (a mainstay of the new millennial American independent scene) is ordinarily beautiful, not movie-star knockout. Florence is self-conscious and unsure of herself, which is why she'll drive Greenberg around (he doesn't drive) even after he's walked out on her twice.
Uneventful (the dog gets sick, and, uh, that's about it), "Greenberg" resembles the kind of films Gerwig has been making ("LOL," "Baghead"), but on a bigger budget and with one of Hollywood's most accomplished cinematographers on board (Harris Savides, whose credits include "Zodiac" and "Milk"). That is, it coalesces around tentative, half-formed ideas about how to be a person in the world. "Greenberg" shows that young people aren't the only ones wondering what they're to make of themselves and whether it's already too late.
Its best sequence, the climax, is an impromptu house party in which Greenberg finds himself pontificating, stoned, before a bemused audience half his age -- and at long last manages to accept himself.
It's a small victory but worth savoring.