I always thought his comedic skills (in “Jeannie”) were top-notch, and he was actually rather underrated.
As a human being, well... I read a long, long interview of him (where he went on endlessly about his dope/alcohol use, and his pursuits of ‘opening his mind’), and he came across as one of the most ridiculously self-absorbed personalities that I could imagine. Very juvenile and stunted mind, incapable of seeing anything beyond himself. Downright cringe-worthy, reading that interview.
I do know he had some very odd habits. Apparently he never spoke on Saturdays.