Here is a sampling of what they had to say:
Rob Kendt in his Broadway.com Review of the off-Broadway production, originally published February 27, 2006: "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 the paper reprinted excerpts from Brantley's review of the off-Broadway mounting, published February 28, 2006: "Mr. McDonagh isn't trying to elicit the poetry in surreally stylized violence or the aesthetic content in shades of red. There's nothing pretty about the gruesome mess in which these gun- and razor-toting characters, members of splintered splinter groups of the Irish Republican Army, find themselves. And they seem to regard as merely mundane the abominations they commit in the name of causes they can't always remember. But they might as well face it, they're addicted to blood. So, this play suggests with devilish obliqueness, are we."
Michael Kuchwara of The Associated Press: "The bloody mayhem that envelops Martin McDonagh's The Lieutenant of Inishmore explodes as effectively on Broadway as it did off-Broadway. In fact, McDonagh's dark, dangerous satire on Irish terrorism plays even sharper, surer and funnier in the larger confines of Broadway's Lyceum Theatre… McDonagh, London-born but with roots in Ireland, is a natural storyteller with an idiosyncratic way with a phrase. He's got that great Irish gift of gab, conversations that a strong cast, under the astute direction of Wilson Milam, deliver with remarkable finesse."
Elysa Gardner of USA Today: "Though not as deeply or intricately disturbing as Pillowman, Inishmore is a lot gorier. Cat lovers and the generally squeamish should be advised that feline blood—fake, of course—is spilled, though not in nearly as great abundance as fake human blood. But however extreme the violence and collateral damage in this very, very dark comedy, there's nothing gratuitous about it. The action in Inishmore is, like the dialogue, stunningly taut and efficient. At a time when irony is being given a bad name, in theater and elsewhere, by writers who aren't nearly as clever as they think they are, McDonagh's fierce, unpretentious wit is a treasure. Better still, there's a message in his madness."
Linda Winer of Newsday: "This remains good, smartly stupid fun, an unrepentantly violent, Grand Guignol bloodbath about splinter groups of nationalist splinter groups: a chop-shop of a world in which mutilated cats are mourned while people are just dead meat. Bellowing Irish accents are a bit harder to comprehend in the larger theater and I still think the momentum is hurt by an unnecessary intermission."