Here is an overview and what critics have said about this novel...
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From the Publisher
“Dashiell Hammett . . . is a master of the detective novel, yes, but also one hell of a writer.” –The Boston Globe
“The Maltese Falcon is not only probably the best detective story we have ever read, it is an exceedingly well written novel.” –The Times Literary Supplement(London)
“Hammett’s prose [is] clean and entirely unique. His characters [are] as sharply and economically defined as any in American fiction.” –The New York Times
New York Times Book Review
If the locution 'hard-boiled' had not already been coined it would be necessary to coin it now to describe the characters of Dashiell Hammett's latest detective story. . . there is plenty of excitement. -- Books of the Century; New York Times review, February 1930