frustrating genius
I used to love Asimov as a teenager, but as I got older I became more conscious of his flaws that largely spoiled his work.
His dialogue is clunky for a start. He has an annoying habit of illustrating his points and ideas repeatedly. So you often find characters explaining things to you at exhausting length, yet again, when all the time you were wishing they'd just get on with things. And his characters inter-relationships never sounded real. Just people talking at each other. He also couldn't write female characters for toffee.
There's no doubt he was a genius writer and visionary, but I find reading him frustrating now.