Well he's not wrong. Characters wouldn't be Clarke's strong suit. For well-realised and fully developed original situations, though, he's hard to beat.
FWIW Pat is wrong about SF. I know what he means by having to use it to being a 'retreat', but the same true of almost all fiction, all entertainment. The indirect approach can sidestep otherwise immovable preconceptions, and create allegories that far outlive the context of their creation: Gulliver's Travels, Frankenstein, 1984, Farenheit 45, Judge Dredd, there's a reason these are all part of our cultural and conceptual lexicon.