Catherine Mayer interviewed me for about 2 hours for this piece.  While I can hardly claim to know “who is David Cameron”, I think that Catherine captured some really valuable things about his personality that were not in the public domain before.  For example, she writes:

“Yet despite such constant self-exposure, an easy affability that reads as openness and his willingness to perform without scripts or teleprompts, Cameron remains an enigma. Part of what makes him hard to categorize is that he’s above all a pragmatist, priding himself on reasonableness rather than ideological fervor.”

I think that this captures an important part of his personality.
While I never became friends with him, I respected and admired his intellect and abilities at the time and now.  As Catherine writes:

“He came to Oxford equipped with a much more complete road map of what he wanted to do,” says Guy Spier, who also attended Sinclair’s tutorials and now runs an investment firm in New York. He remembers Cameron as an outstanding student: “We were doing our best to grasp basic economic concepts. David — there was nobody else who came even close. He would be integrating them with the way the British political system is put together. He could have lectured me on it, and I would have sat there and taken notes and learned how British politics was put together.”