TBH most of it is absolute tosh, but with the best of it the setting is integral to the story. Some of it has stayed with me all my life - John Wyndham's The Chrysalids, Ray Bradbury's The Illustrated Man and The Martian Chronicles, Olaf Stapledon's Sirius.I never quite got SciFi.
Of course some people read nothing but SciFi and Fantasy. That's depressing, especially in an adult.
