I suppose that, like many others, my introduction to the work of Arthur C. Clarke was through his science fiction, rather than his science popularisation. I suspect that it was his Childhood's End that I read first and I read many more of his more than 100 titles subsequently. He was never my favourite SF writer, however, I think that Ray Bradbury filled that role for me, although H.G. Wells would have been a strong contender.
Aged 90, he has now moved on and the Official Google Blog has a very nice appreciation of him from Vint Cerf, along with a video of a short farewell statement, which he made just before his 90th birthday. One can tell that, though he was wheel-chair-bound, his mind was as active as ever.