A man who knows exactly what he is writing about and has written it marvellously well
Ernest Hemingway,

O'Hara occupies a unique position...He is the only American writer to whom America presents itself as a social scene in the way it once presented itself to Henry James, or France to Proust
Lionel Trilling, New York Times

O’Hara understood better than any other American writer how class can both reveal and shape character
Fran Lebowitz,

A fascinating character study by one of America's most underrated storytellers, but there are other rewards as well. O'Hara's dialogue is unerringly authentic and his narrative passages as graphic as a photograph
Los Angeles Times

His ear for dialogue is legendary, and he evoked New York cabbies, Hollywood producers and cheap hoods like Pal Joey as easily as he did Park Avenue socialites... Few authors today write convincingly of matters involving public life and private morality - they tend to do one or the other. But O'Hara could intertwine them in a five-page sketch or an 800-page epic.
Washington Post