I like most kinds of fiction, mostly for the same qualities, none of which is specific to a single genre. But what I like in and about science fiction includes these particular virtues: vitality, largeness, and exactness of imagination; playfulness, variety, and strength of metaphor; freedom from conventional literary expectations and mannerism; moral seriousness; wit; pizzazz; and beauty.
Let me ride a moment on that last word. The beauty of a story may be intellectual, like the beauty of a mathematical proof or a crystalline structure; it may be aesthetic, the beauty of a well-made work; it may be human, emotional, moral; it is likely to be all three. Yet science fiction critics and reviewers still often treat the story as if it were a mere exposition of ideas, as if the intellectual “message” were all. This reductionism does a serious disservice to the sophisticated and powerful techniques and experiments of much contemporary science fiction. The writers are using language as postmodernists; the critics are decades behind, not even discussing the language, deaf to the implications of sounds, rhythms, recurrences, patterns—as if text were a mere vehicle for ideas, a kind of gelatin coating for the medicine. This is naive. And it totally misses what I love best in the best science fiction, its beauty.
Ursula K. Le Guin, introduction to A Fisherman of the Inland Sea, 1994.