It is fascinating to observe how the threatened becomes the one who threatens as the power shifts and moves between these two as they face off. Dynamics surrounding law and order for Hank versus desire for empire building and working outside the bounds of conventional constraints for Walt as he tries to rationalize an end game for them ("what's the point?" asks Walt with typical nihilistic aplomb). Hank is just beginning to see the transformation and emergence of Heisenberg within Walt in that moment. We have had the privilege of watching his evolution (or devolution depending on your perspective) throughout the series but we must remember that Hank is observing it for the first time. You can see the epiphany in his eyes. The scene begins, in part, by Walt saying, "I don't like the way you are looking at me right now" and ends with Hank saying "I don't even know who you are". Chilling.
It is hard to imagine that this scene will not go down in the annals of television history along with Al Pacino's kiss in the Godfather 2. At a minimum one or both of these fine actors deserve the Emmy this year for this performance alone!