I don't know if he is a good person - certainly I think he has charisma which is sadly lacking in many politicians today. He also seems close to his family; his sister has written about him on occasion (although she has the opposite view to him regarding the EU - am I allowed to say that?).
I found his WDYTYA programme very interesting too - more than I can say for some of them.
As for Prime Minister material - well, I think there is an intelligent, serious side behind that public persona, but personally I'm not sure whether I want to find that out.
I don't think he colours his hair - his father has always been that blond too, as are the rest of the family.
If we're discussing whether or not having affairs detracts from being a good politician, how about Jennie Lee, David Blunkett, Robin Cook, Paddy Ashdown, Ron Davies, John Prescott, Cecil Parkinson, Alan Clarke, Jeremy Corbyn etc - the list is endless. It seems to be almost a pre-requisite for the job of politician - although it is a moot point whether or not some of the above were good ones.