Initially, the novel fared poorly in the United Kingdom and the United States, selling only 3,076 copies between 1907 and 1914. The book fared slightly better in Britain, yet no more than 6,500 copies were printed before 1914. Although sales increased after 1914, it never sold more than modestly during Conrad's life. It was published to favourable reviews, most agreeing with the view of The Times Literary Supplement that it "increase[d] Conrad's reputation, already of the highest".[22] However, there were detractors who criticised the novel's "unpleasant characters and subject". Country Life magazine called the story "indecent" and criticised Conrad's "often dense and elliptical style".[22]
The Secret Agent has come to be considered one of Conrad's finest novels. The Independent calls it "[o]ne of Conrad's great city novels"[23] whilst The New York Times insists that it is "the most brilliant novelistic study of terrorism".[24] The Pequod called the book “one of Joseph Conrad's best books,” and rated the book a 9.5 out of 10.0.”[25] In a 2016 review, The National Review said the book “may be the first great novel of global terrorism.”[26]
