[In Doorways in the Sand] Zelazny has succeeded in that most difficult creation in science fiction: a genuine three-dimensional character. He's Fred Cassidy, a 29-year-old perpetual student in an unnamed twenty-first-century university, with acrophilia which expresses itself in simian rooftop ramblings…. Zelazny uses his dry chuckle, superb writing, and a fascinating narrative to make the reader want to reach out and shake Cassidy's hand.

Dan Miller, "Science Fiction: 'Doorways in the Sand'," in The Booklist (reprinted by permission of the American Library Association; copyright © 1976 by the American Library Association), Vol. 72, No. 15, April 1, 1976, p. 1095.