One of the first things I read of Clarke's was Against the Fall of Night, which I'd liked. But I was very confused when I later read The City and the Stars, because I was not at the time aware the second was a revision of the first. I just kept thinking "Surely I have read this before!"

He wasn't one of my favorites ('fraid - all but the late books - Heinlein was that), but I always liked his books.