[The Dream Master and Isle of the Dead are two] very different novels even though similar in "style" (i.e. in diction and in making much use of myth). The first is a near future novel of psychological realism and tragic overreaching concerned with "neuroparticipant therapy" in which the psychiatrist participates in and shapes the dreams of the patient, and is in my opinion second only to [Thomas M. Disch's 334]…. The second is a bang-bang interstellar adventure story, a puerile daydream, albeit one of the sixties rather than the twenties, and thus mixing Philip Marlowe with John Carter to produce a hero of a more "mature" type.

R. D. Mullen, "Books in Review: 'The Dream Master' and 'Isle of the Dead'," in Science-Fiction Studies (copyright © 1976 by R. D. Mullen and Darko Suvin), Vol. 3, No. 10, November, 1976, p. 303.