It would be interesting to know AlphaGo's estimated probability of winning as the game progressed; presumably we can see directly how worried it was at any given point in the game. And thus get another sense of whether it ever really felt threatened by Sedol.

At this point, the match is won, but games 4 and 5 will commence. The question shifts from whether AlphaGo is better than humanity's best, to whether humanity can even have a chance of beating AlphaGo in a single game. And so far, it sounds like the answer is likely to be a resounding no.