George Orwell and Aldous Huxley were two writers who initially established themselves not only in the world of realist fiction, but also as effective observers on society. As a result, their later novels Nineteen Eighty-four and Brave New World are heralded as two of the greatest science fiction novels ever written, with literary purists even willing to make allowances despite the sci-fi leanings. Perhaps it is John Brunner’s misfortune that his career was established in the world of science fiction. When Stand on Zanzibar was published in 1968, only those within the genre took notice of its qualities. As poignant literature that transcends genre, it too comments with profound relevance on the human condition.
In a truly great science fiction novel, you'll find the creation of an often fantastical land or situation effortlessly and cleverly grounded with enough humanity and realism for you to genuinely invest your time and emotions.