Noah Baumbach is easily one of the four best American filmmakers working today. However, his films can be difficult, focusing on unpleasant characters who create unpleasant situations. Greenberg is like that, taking the romantic-picture genre and covering it in the slime and dirt that other films bury beneath layers of schmaltz and false closure. Ben Stiller plays the titular Roger Greenberg, a failed musician and 40-year-old loser who’s just been discharged from a mental hospital. He comes to Los Angeles and engages in inappropriately assholish behavior with Florence Marr, his brother’s 24-year-old assistant. Florence is played by Greta Gerwig, who should become a big star based on her expressiveness and subtlety, but who’ll probably become a little star, because she’s too good to ever appear in a movie about a white woman who redeems a bunch of inner-city youths and then becomes secretary of commerce. The film is shot by Harris Savides, for whom they need to invent a word that’s much stronger than “genius”; the soundtrack is rich with tidbits of early ’90s underground pop and its more recent descendents. Greenberg’s greatest asset, though, is Baumbach’s dialogue, which all sounds like accidental poetry that was found by monitoring every late-night DJ for the past 100 years and distilling the essence into 107 perfect minutes.