I know several people who've met him at various Prince's Trust, Duke of Edinburgh Award, etc things and they've all said how he impressed them as a decent bloke. Somewhat posh and obviously moving in different circles, but not rude or arrogant with it.
I remember reading something about how he went to some inner-city ghetto to visit a scheme for reformed drug dealers or something similar, he shooed his security out of the room because he wanted to talk to them alone, the security/bodyguards were then cr*pping themselves outside with Charlie alone in the room with a number of black gangstas, but after half an hour or so they all emerged swapping jokes.