I rather think Flowers for Algernon is a bit of a one-off. DK has written very little other science fiction. Most of what he has written seems to revolve about Flowers for Algernon.
Apparently the book didn't please everyone:
"Daniel Keyes' acclaim, however, was not universal. Some critics found his novel pornographic, sexually explicit, and irreligious. Consequently, censors kept Flowers for Algernon on the top of their "banned books" list for years (Small, 254). Though best known for Algernon, Keyes' prolific body of published works also includes novels The Touch (1968), The Fifth Sally (1980) and Unveiling Claudia (1986), the non-fiction true-crime novels The Minds of Billy Milligan (1981) and The Milligan Wars (1986), many short fictional pieces, and the recent memoir, Algernon, Charlie and I : A Writer's Journey (2000 "
This link gave me the above information.
http://www.bookrags.com/notes/alg/BIO.htm
I enjoyed the story immensely when I read it, and found it moving, but hardly pornographic.
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