[Santaroga Barrier] is exciting and suspenseful; but there is a good message here as well. Santaroga seems utopian: perfectly adjusted, with no crime or reported mental illness. But there are failures—mental cripples who could not handle the Jaspers. Even the psychologist's own professional experience fails to help him under the drug's high. The message is not judgemental: Herbert likes to explore the possibilities of altered states of consciousness…. When Dasein overdoses on the drug, we are left wondering whether what is left is an omniscient superman, or a euphoric idiot. (p. 6)

Robin Adams, in Young Adult Cooperative Book Review Group of Massachusetts, October, 1977.