"While We're Young" is an enjoyable but limited look at both Millenial-Generation X relations and growing old. Written and directed by indie darling Noah Baumbach, the film reunites Baumbach with Ben Stiller after their 2010 work on "Greenberg." The reunion has Baumbach and Stiller treading familiar ground, and Baumbach again sets up Stiller in a more serious role than his more comedic turns, and the film makes thorough use of his ability to portray the prickly, nebbish Josh. 

Baumbach also leans toward casting another of-the-moment quirky actor; for "Greenberg," it was the plucky blonde Greta Gerwig, then fresh out of her mumblecore days and something of a hot commodity. For this film, Baumbach picks up "Girls" actor Adam Driver, who admirably dives into his role as Jamie, a fedora-wearing hipster.

The relationship between Stiller and Driver propels the movie in fits and starts through its hour and a half runtime. In one scene, Stiller and Driver pedal newly-bought fixies down a busy New York street, uplifting music playing as the two unlikely friends drive each other's bikes and hold up traffic. Like that scene, Baumbach's screenplay has a promising start, and both the establishment of the tableau and the inevitable meet-cute are done refreshingly and in keeping with Baumbach's charmingly straight-forward approach.

Eventually though, both the narrative and Stiller's character throw out their back and have to pull over. "While We're Young" does an admirable job establishing the characters, including the formidable Naomi Watts (Stiller's wife, Cornelia) and the doe-eyed Amanda Seyfried (Jamie's wife, Darby). Baumbach's characters never feel stilted, and feel strongly worth considering.

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This strength, however, is also the film's greatest weakness, as the characters end the film almost perniciously underused and underexplored. Seyfried in particular does a spectacular job lacing her traditionally meek muse with a current of emotional neglect and joking-but-not-really hostility, and is rewarded with an unceremonious final scene send-off and a plot position that exists to highlight the neediness of Josh.

Watts as well is press-gacnged into service of Josh's character advancement, an unfortunate decision that seemed almost impossible to do considering how capable and alive she seems at the movie's outset: she supports the couple's lifestyle on her salary alone, and seems both a quicker wit and friendlier person than her much-less successful than her documentarian husband.

Driver himself narrowly holds the focus of Baumbach's lens, with thanks due in equal parts to his slimy but electric screen presence and Baumbach setting him up as the pincushion for barbs against the neo-authentic Bohemianism and kitsch-worship of the Brooklyn hipster lifestyle. 

Baumbach has interesting observations to make about the appeal of living with a chicken, taking mescaline and “vomiting out your demons,” and wearing a fedora, and even when he gets caught up in now outdated canards about listening to music on vinyl and artisanal ice cream, he does it with forgivable sincerity. Jamie and Darby bring up an interesting and often funny contrast to the no nonsense, no fun Josh and Cornelia, and when these two couples are together, "While We're Young" is a lithe, energetic film with a lot to say and formidable characters to say it with.

Sadly, that film lasts only 40-odd minutes, and "While We're Young" eventually eschews its focus on characters to dive into a tangentially related plot about success, authenticity and documentaries, of all things. The meandering plot leaves an almost artificial taste in its leaps and bounds, which is especially noticeable after the (almost artisanal) flavor of Baumbach's character building. Baumbach keeps things light, and never does the film forgo its comedic chops, but "While We're Young" ends not with a poignant longing for ones youth, but a much sadder longing to return to the excellent film that it almost was.

Reach Contributor Andy Vasoyan here.