I'm as big an Asimov fan as anyone, but I generally agree that his later novels were weaker. He set himself the challenge of merging the Robot universe with the Foundation universe and I'm not sure it was a good idea. I have always said that his short stories were his best work. I recently heard the radio adaptation of "Hostess" and was reminded was a great story that is.
I was a fan of his science essays before I read his fiction. I taught myself physics via those essays before I learned it in High School. But even more importantly, I learned how to think like a scientist. I owe him a huge debt of gratitude for that, which, fortunately, I was able to express to him once in person.
Yes, although he wrote over 400 books, most of the good ones were in the first 100.[1] There were a lot of junk books in the later years. That happens to working writers.
At least Asimov didn't get stuck writing movie tie-ins.
Some good SF writers have had to write movie tie-in novels to pay the rent. Alan Dean Foster, who wrote some excellent novels in his own universes, has ground out too many Star Dreck, Star Wars, Alien, Terminator, and Transformers tie-ins.
Foundation series are still my favorite. I'm on the Caves of Steel now. Interesting that the whole "robots are taking our jobs" is presently playing out, and how being "declassified" relegates one to a life of poverty.
I was a fan of his science essays before I read his fiction. I taught myself physics via those essays before I learned it in High School. But even more importantly, I learned how to think like a scientist. I owe him a huge debt of gratitude for that, which, fortunately, I was able to express to him once in person.