I was never a huge fan of his music (enjoyed some of it) but I was always impressed by his imagination, inventiveness and creativity.
He didn't seem to spend his time pontificating, telling everyone how the world should be organised, or claiming that he had some great 'message' for society. He just got on with demonstrating all the weird and wonderful ways he could organise his world. He didn't seem particularly pompous, self-important or up himself, unlkike some pop 'icons'. He seemed to be having fun.
In the few interviews I ever saw, he seemd surprisingly normal, articulate, relaxed and at ease with himself. I don't remember him ever being agressive, hostile or even particularly rude about anyone.
And he had the massive advantage of - as far as I know - never letting himself (or his careeer) be fucked Yoko Ono.