Agreed -- he did his research. I was imagining him having to be equally knowledgeable in many other domains when interviewing political leaders and so forth, and came away impressed. Although I'm sure he has a team that helps prepares the questions, he still has to think on his feet a bit.
The only place where he perhaps came off uninformed is when he implied that Google hadn't acquired any companies in 2012, when in fact they've acquired dozens. But that's not a very substantive mistake.