The reviews of Slaughterhouse-Five have been largely positive since the 31 March 1969 review in The New York Times newspaper that glowingly concedes: "you'll either love it, or push it back in the science-fiction corner." In 1970, its publication year, Slaughterhouse-Five was nominated for a best-novel Nebula Award and for a best-novel Hugo Award. It lost both to The Left Hand of Darkness, by Ursula K. Le Guin. In 1998, the Modern Library ranked Slaughterhouse-Five eighteenth on its list of the 100 best English-language novels of the 20th century. It also appeared in Time magazine's list of the 100 best English-language novels written since 1923.
Slaughterhouse-Five has been the subject of many attempts at censorship, due to its irreverent tone and purportedly obscene content. American soldiers use profanity, his language is irreverent and the book depicts sex. It was one of the first literary acknowledgments that homosexual men, referred to in the novel as "fairies", were among the victims of the Nazi Holocaust.
In the USA it has at times been banned from literature classes, removed from school libraries and struck from literary curricula. In 1972 it was banned from the public schools of Oakland County, Michigan. The circuit judge described the book as "depraved, immoral, psychotic, vulgar and anti-Christian."
The U.S. Supreme Court considered the First Amendment implications of the removal of the book, among others, from public school libraries in the case of Island Trees School District v. Pico, [457 U.S. 853 (1982)] and concluded that "local school boards may not remove books from school library shelves simply because they dislike the ideas contained in those books and seek by their removal to 'prescribe what shall be orthodox in politics, nationalism, religion, or other matters of opinion.'" Slaughterhouse-Five is the sixty-seventh entry to the American Library Association's list of the "Most Frequently Challenged Books of 1990–1999" and number forty-six on the ALA's "Most Frequently Challenged Books of 2000–2009". Slaughterhouse-Five continues to be controversial. In August 2011, the novel was banned at the Republic High School in Missouri. The Kurt Vonnegut Memorial Library countered by offering 150 free copies of the novel to Republic High School students on a first come, first served basis.
The bombing of Dresden in World War II is the central event mentally affecting Billy Pilgrim, the protagonist. Within, Vonnegut says the firebombing killed 135,000 German civilians; he cites The Destruction of Dresden, by David Irving. Later publications place the figure between 24,000 and 40,000 and question Irving's research.
Critics have accused Slaughterhouse-Five of being a quietist work, because Billy Pilgrim believes that the notion of free will is a quaint Earthling illusion. The problem, according to Robert Merrill and Peter A. Scholl, is that "Vonnegut's critics seem to think that he is saying the same thing [as the Tralfamadorians]. For Anthony Burgess, "Slaughterhouse is a kind of evasion —in a sense, like J. M. Barrie's Peter Pan —in which we’re being told to carry the horror of the Dresden bombing, and everything it implies, up to a level of fantasy..." For Charles Harris, "The main idea emerging from Slaughterhouse-Five seems to be that the proper response to life is one of resigned acceptance." For Alfred Kazin, “Vonnegut deprecates any attempt to see tragedy, that day, in Dresden... He likes to say, with arch fatalism, citing one horror after another, 'So it goes'." For Tanner, "Vonnegut has... total sympathy with such quietistic impulses." The same notion is found throughout The Vonnegut Statement, a book of original essays written and collected by Vonnegut’s most loyal academic "fans"."