Here is a sampling of what they had to say:
Edward Karam in his Broadway.com Review: "For all the energetic corrosiveness in LaBute's portrait of Tom's office, visually realized by designer Louisa Thompson with tellingly opaque windows and dull gray metal, it rings false. Even with much of the play set around his desk, we never find out what kind of work Tom does; it's just a generic business. In the real world, whether his company sold insurance or armored vehicles, Tom would have recourse against a shrew like Jeannie, as well as against Carter, and higher-ups would put a stop to their intrusions. LaBute raises honest, difficult questions about human nature: Is it possible to live without allowing peer pressure to influence one's choices or behavior? How important are looks compared to decency? What compromises should one make in a relationship? The play ultimately relies more on its fine actors to make us care about the answers than on clarity in its arguments."
Ben Brantley of The New York Times: "Fat Pig is also the most emotionally engaging and unsettling of Mr. LaBute's plays since Bash, his scary bill of short dramas five years ago about the un-Christian behavior of four Mormons. This is partly because Mr. LaBute lets his audience step over the boundaries of clinical observation to empathize with his protagonist--a charming, handsome rising-executive type named Tom--and with the woman he falls for, Helen, a warm and witty librarian who is conspicuously overweight. But a show that still might have been merely a point-proving exercise is immeasurably enriched by the skill and honesty of the two young performers who portray Tom and Helen. They are Mr. Piven, who makes a smashing New York stage debut as Tom, and Ashlie Atkinson, a recent graduate of the Neighborhood Playhouse, whose appealingly drawn Helen implicitly and fully condemns the nasty hollowness of the play's title."
Frank Scheck of The New York Post: "In this play, LaBute balances black humor and social commentary in a less schematic fashion than he's done previously. The relationship between Tom and Helen, beginning with the beautifully written, hilarious opening scene, is depicted with a tenderness that makes the difficulty of their situation all the more poignant… LaBute's dissection of how societal pressures affect relationships is astute and up-to-the-minute relevant, though the ending feels abrupt and rather forced. But overall the play works beautifully, thanks to the pungency of the writing, the fluid direction by Jo Bonney, and the excellent performances by the ensemble, with particularly moving work by Piven and Atkinson as the weight-crossed lovers."
Howard Kissel of The New York Daily News: "Under the direction of Jo Bonney, the cast makes what sometimes comes perilously close to sitcom a polished, oddly elegant piece of theater. This is particularly true of Russell and McCarthy, who could easily come across as adolescent. Russell has a hilarious angry monologue. McCarthy has a stylishness that recalls Tony Randall's super graceful work in the immortal Pillow Talk. Piven is splendid at conveying Tom's genuine concern for Helen as well as his bewilderment at his responses to her. Atkinson triumphs as Helen, making both her savvy humor and her underlying sadness palpable. LaBute's play succeeds in the perverse goal he sets. It is, for most of the evening, giddily entertaining, but when it ends you are overcome by a sense of poignancy and awkwardness."
David Rooney of Variety: "In Fat Pig, an uncharacteristic empathy for the weakness of a white-collar male ruled by rigid peer expectations steers the playwright from his customary terrain of emotional brutality to the entrapment of self-image. And unexpectedly, the uneven play is most absorbing not when chronicling the virulent behavior that is the writer's stock in trade but when assessing its casualties, sympathetically embodied by Jeremy Piven and likable newcomer Ashlie Atkinson… Divided into seven redundantly titled scenes--'That First Meeting With Her,' 'The Work Friends Figure It Out,' etc.--the action could be more forcefully shaped by Bonney, but remains engrossing nevertheless."
Linda Winer of Newsday: "The shock of the evening is how shockingly cautious it is. Fat Pig is a title with a play on it, rather than the other way around. Ashlie Atkinson is admirably courageous as Helen, the smart, sexual and credibly self-protective librarian who tells her surprising new suitor, 'I feel OK with who I am. The trick is getting other people to be OK with it…' LaBute works overtime to make Helen's competition a strong woman, not a bimbo, but this strength comes out as brittle, physically aggressive and pathetic. And, lest the deck is not stacked high enough against dramatic credibility, Tom finally introduces his controversial new woman to his friends at an office beach party. Watching Helen decide what to wear is a poignant moment, but not enough to keep the plot from seeming an excuse to put her in a bathing suit."