At Tuesday, March 18, 1:30am local time in Sri Lanka, the world lost a great man. I deeply enjoyed the Space Odyssey books (though I don't have much recollection of 2061, and 3001 is sub-par compared to 2001 and 2010), and Childhood's End and Light of Other Days remain two of my favourite science-fiction novels.
To me, Clarke succeeded because his stories are not just pure flights of fancy. Quite often, his visions are just barely out of reach of the current progress of science--it inspires a sense of hope and motivates research. Furthermore, he is unafraid of social commentary: something that makes his stories so much more satisfying emotionally.