Here is a sampling of what they had to say:
Rob Kendt in his Broadway.com Review: "Many partisans clearly find McDonagh's shock treatments exhilarating; if they have never seen a play by Tracy Letts or a film by Quentin Tarantino, they may even find them novel. Personally, to use the coinage of a touchy cop from last year's creepy-crawly interrogation fantasia The Pillowman, I only half-trust McDonagh's instincts as an entertainer. With The Lieutenant of Inishmore, actually, make that less than half. A series of cheap shots, literally, at the loony fringes of the Irish Republican cause, the play paints true believers, opportunists, and passive bystanders in such cartoonish terms that the angry sneer of its satire--what McDonagh has called his 'pacifist rage' at the absurdly ceaseless cycle of bloodshed over Ulster--can't be taken seriously."
Ben Brantley of The New York Times: "If your stomach is reasonably strong, you should find the disgusting spectacle that opened last night at the Atlantic Theater Company appallingly entertaining. More improbably, you should also find it enlightening… Every element of plot and tone in Lieutenant is established here with Aristotelian precision. However unorthodox his subject, Mr. McDonagh is a structural classicist, one of the few contemporary playwrights never mind filmmakers who never leaves loopholes in his plot… Lieutenant is brazenly and unapologetically a farce. But it is also a severely moral play, translating into dizzy absurdism the self-perpetuating spirals of political violence that now occur throughout the world."
Frank Scheck of The New York Post: "This latest work by the author of The Pillowman again demonstrates its creator's affinity for dark and disturbing material that somehow manages to be ruthlessly funny. The tale of a vicious and psychopathic IRA assassin who's obsessed with his cat, it also reveals itself as the most bizarre love story you'll see onstage this year. The play, which actually predates The Pillowman but is only now being given its American premiere by the Atlantic Theater Company, lacks the other's thematic and emotional resonance. A bloodily slapstick tale of violent revenge that turns out to be the theatrical equivalent of a slasher movie, it is best appreciated for its sheer bravura audacity."
Howard Kissel of The New York Daily News: "If Monty Python had ever tackled the issue of Irish terrorism, they might have created something as wild, as brilliant and as weirdly exhilarating as The Lieutenant of Inishmore… To reveal much more might take the edge off Inishmore's abundant, ghoulish humor. What is remarkable about the writing is its rigorous logic."
Michael Kuchwara of The Associated Press: "Be warned. The play, set in 1993 Ireland, is brutal, bloody-and often blisteringly funny... Fans of Quentin Tarantino and Sam Peckinpah will feel right at home. Yet, believe it or not, McDonagh is a moralist. The futility and even stupidity of his characters are never in doubt in this darkly comic tale. He skewers with a deft hand... The Lieutenant of Inishmore is not for the faint of heart, but those willing to follow McDonagh throughout his murderous journey will be in for quite a ride."