Characterization is crucial.
And since many of their readers are not familiar with technical jargon, the stories must be written in clear, understandable prose. Payment is 20 cents a word. And they do not accept unsolicited poetry or simultaneous submissions but will consider a self-contained story that is part of a novel, or may later be developed into one. I suppose that SF fans should welcome this sort of thing with open arms. After all, a future in which paper books are replaced by sleek disposable video displays was imagined way back in the Golden Age of the 30s and 40s, along with personal jet packs and interplanetary travel.