Well, Napolitano is viewed by both Dems and Reps as a good choice. Obama has said that Gates would remain for a year at this point and then be re-evaluated. Obama has one thing definitely going for him: he listens and he wants people in positions from all sides. He's not exclusive in his choices and that makes him unusual since he's fair. Certainly he's not "left-wing". I don't think he ever said he was or that anyone has ever said he was.
He did promise change: that you'd have a president that would listen and make a difference towards the positive, not the negative. So far, he's been pretty much on course.