In the cold light of adulthood it is unfortunately not as good as my inner child remembers. Nowhere near as bad as Rowling, who is an awful writer, but still pretty bad. To be fair to Rowling her first book actually introduced some good ideas, the rest were pretty much universally crap.
Some of Asimov's themes and ideas are also feeling very dated now too, he seemed to be heavily influenced by the US/Russia situation and early electronics and those inspirations have not stood the test of time.
A visionary in his time and for a generation afterwards, but I'm starting to doubt he'll be much read in 10 or 20 years time.