Nobody has mentioned ambition yet, I think he has perhaps the most ambition and drive of any manager. It's the reason he swaps clubs fairly often, I remember in an interview with him he also explained his long term goals (which he is about to achieve, winning the league in the top three in the world - Italy, Spain and England). I also remember when he won the league cup with Chelsea and said it meant nothing to him, this again, is due to the high standards he sets himself.
I also think he knows how to play mind games just as much as Fergie does and I think over the last season and a half he has definitely got into Guardiola's head.