"Greenberg" aims to recapture the raw flavor and psychological acuity of 1970s character portraits like "Five Easy Pieces"--but the character in question is completely of the moment. Neurotic and anxious Roger Greenberg (Ben Stiller) comes to L.A. to stay in his brother's house, where he reconnects with old bandmates and falls, with painful awkwardness, into a relationship with his brother's personal assistant, Florence Marr (Greta Gerwig, sweetheart of the "mumblecore" movement). But this movie is not about plot--it's about human frailty and finding a moral or spiritual significance in caring for a dog or driving someone on an errand. Stiller sheds his usual bag of twitchy tricks and conveys the brittle spirit of a man defeated by his own intelligence. Gerwig has an odd, hapless charm; she makes aimlessness appealing. As a romance, the movie falters--while it's obvious why Roger would be attracted to Florence's youth and vulnerability, it's less clear why Florence wouldn't be repelled by Roger's sometimes-cruel instability. But writer-director Noah Baumbach ("The Squid and the Whale") has gotten even better at capturing the history of two people with brief, incisive strokes; Roger's prickly history with his friends becomes vividly clear in a few conversations. As a core sampling of the contemporary psyche, "Greenberg" is rewarding. Also featuring excellent performances by Jennifer Jason Leigh ("eXistenZ") and Rhys Ifans ("Notting Hill"). "--Bret Fetzer"