In the past few years, Beanie Feldstein has emerged as the reigning avatar for a certain type of teenage girl: short on popularity but huge on personality, bursting an intelligence that won't be properly appreciated until adulthood, and definitely Way Too Much according to the rules of acceptable young femininity.

Her latest film, How to Build a Girl, is another in that collection. This time, Feldstein plays Johanna Morrigan, a teen who longs to escape her drab, working-class existence in 1990s Britain — and gets the chance to do just that when she reinvents herself as a rude, crude, notoriously vicious music critic.

It's one thing for a kid to still be figuring herself out; it's another for the film about her to be.

Coky Giedroyc directs How to Build a Girl from a screenplay by Caitlin Moran, based on Moran's own semi-autobiographical novel, so it's no surprise that language is the film's strong suit. The dialogue sparkles, whether in offhand exchanges or written diatribes. How to Build a Girl might be worth seeing just for the opportunity to arm yourself with quotes and phrases for everyday use.

Moran spreads her gift among all the characters in the cast, including the role models (Elizabeth Taylor, Sigmund Freud, Sylvia Plath) whose pictures Johanna has pinned to her wall, and who occasionally converse with her, in a cute fantastical touch. But she reserves most of the best bits for Johanna herself. She gets such perfect turns of phrase ("I have nothing to wear for who I need to be," she moans while staring into her closet) that, unlike so many of her fictional counterparts, she's utterly believable as an in-demand wunderkind.

Clever quips only get a movie so far, though, and How to Build a Girl stumbles on other fundamentals. Feldstein brings a disarming guilelessness to Johanna, so that even at her hardest, cruelest, and most self-loathing, we never lose sight of the eager young fangirl she used to be — but the storytelling is such that Johanna's ups and downs always seem one step ahead of our comprehension.

In part, this seems to be because How to Build a Girl is so enamored of Johanna and her journey that it doesn't want to leave anything out. The film touches upon her blossoming sexuality, her changing ideas about rock music, her complicated relationships with her family, and so on, but doesn't dwell long enough to really grapple with any of them.

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Her dynamic with her failed-drummer dad (Paddy Considine), for example, has enough meat to sustain an entire movie, particularly once he starts projecting some of his own unfulfilled dreams onto her — too bad How to Build a Girl barely even picks at it before tossing it aside for her crush on an earnest musician (Alfie Allen, light-years away from Westeros), and her cool-girl status among her boorish male colleagues, and her distant relationship with her depressed mother, and so on.

It all starts to become rather tedious, since it's hard to care deeply about these developments when the film itself doesn't seem to. How to Build a Girl never loses its sense of humor or its affection for its protagonist, but it does lose its way as the story barrels on.

There's still much to love here, not least of which is that this is a story in which a teenage girl gets to make a monstrous asshole of herself, and then learn from her mistakes rather than be condemned by it. And How to Build a Girl does seem to capture the spirit of its heroine, after a fashion. It's a messy, effusive love letter to messy, effusive girls.

But it's one thing for a kid to still be figuring herself out; it's another for the film about her to be. How to Build a Girl has Johanna come to the realization that she can keep rebuilding and remaking herself, working toward becoming the person she truly wants to become. If only the film itself had gone through its own journey of self-discovery before making it to the big screen.