Peter: Asimov was a terrific pop-science writer. Like many other writers, esp. in the sci-fi field, he was at his best in hastily-written throwaway pieces that he probably sat down to do an hour before deadline. His regular pop-science column in the Magazine of Fantasy and Science Fiction in the 1960s was always the first thing I turned to, and rarely disappointed.
He was next best at short stories. My very first venture in sci-fi magazine buying was Authentic #82, which had Asimov’s story “It’s Such a Beautiful Day.” I can still remember the dreamlike, exquisite thrill of reading that story, on a swing in the family back yard one English summer’s day (not unlike the day the story’s young protagonist discovered). I was hooked, and went on buying Authentic till it folded, around 5 issues later. Sci-fi magazines had a life expectancy somewaht like that of subalterns on the Western Front.
At novel length, though, Asimov was not very good. I shall get hate mail from Asimov die-hards, I’m sure; but in your hearts you know I’m right.