While Mamet's current reputation as an important American playwright is established and secure, American Buffalo was the first of his plays to receive intense critical attention. The play premiered on Broadway in February of 1977 (following its successful 1975 debut in Chicago) to reviews ranging as wide as the characters' emotional highs and lows in the play itself. Clive Barnes, writing for the New York Times, stated that although this play marked Mamet's first trip to Broadway, "It will hardly be his last," for "This man can write." Like Barnes, other admirers of the play called attention to Mamet's ability to recreate the rhythms of everyday speech heard in the conversations of his lowbrow characters. Likening the play to a "jam session for jazz musicians," Women's Wear Daily's Howard Kissel wrote that the "fascination" of the play lies in "noting how the same banal language takes on different colors as we perceive the changing relationships" of the characters. Similarly, Edwin Wilson (writing in the Wall Street Journal) stated that "the language, though limited, is extremely accurate" and that Mamet "has a keen ear for the idiosyncrasies and humor of everyday speech." Perhaps the greatest praise came from Newsweek's Kroll, who likened Mamet to British playwright Harold Pinter (The Homecoming) but with his artistic ear "tuned to an American frequency."

Several reviewers, however, were shocked by Mamet's use of obscenity. For example, Time's Christopher Porterfield described Mamet's dialogue as "forlornly eloquent" and praised his "infallible ear for the cadences of loneliness and fear," but the critic also remarked that Mamet "revels a bit too much in this scatology and blasphemy." He further suggested that if Mamet were to "Delete the most common four-letter Anglo-Saxonism from the script ... his drama might last only one hour instead of two." John Beaufort, writing in the Christian Science Monitor, called the play "excessively foul-mouthed" and remarked that its content (like its language) smacked of "gratuitous sensationalism." (These charges against Mamet's dialogue were renewed when his Glengarry Glen Ross premiered in 1983.)

Like their opinions of Mamet's idiom, critics were also divided in their perception of American Buffalo's themes and reflection of contemporary American life. For example, Irving Wardle, writing in the London Times, stated that a viewer "would have to be tone deaf to miss the music, irony and virtuosity" of Mamet's dialogue—but followed this compliment by describing the play as a "suffocating tedium" where the characters are "at a standstill." The National Broadcasting Company's (NBC) Leonard Probst complained that "the center of the play is missing"; The Daily News stated that Mamet "promises much more than [he] delivers" and labeled his work "a poor excuse for a play." The Wall Street Journal's Wilson wrote that Mamet's characters exist in a vacuum and that they "are too rooted in their own junk, in their own pathetic schemes, in their own fake philosophy to speak for others."

But these critics were not the only voices responding to Mamet's study in anger and shady business—several others praised Mamet for creating an almost allegorical tale of capitalism's dark side. Michael Billington, writing in the British Guardian, called American Buffalo a "deeply political play" and one that "makes its points about society through the way people actually behave." Directly contradicting Wilson's remarks, Victoria Radin (of the Observer,) praised Mamet's ability to show the characters "without patronage and with respect and even love for these little people" who "resemble the little person in all of us."

American Buffalo 's reputation has grown since its first performances. Now regarded...