I love the imagery of this episode. I love that Walt finally realizes that he's never going to redeem himself in the eyes of everyone else but him. To me, this was Walt redeeming himself, for himself. The imagery I'm referring to is that of Walt as an almost wraith like visage; right around the corner in Gretchen and Elliot's, hidden by the pillar in Skylar's house, sitting at the bar while Lydia and Todd were meeting, and, finally, standing over Jesse and Todd as Jesse got his revenge, emotionless, and almost on a different plane of existence, if you will.
Walt accepted his role as the monster at the end of the book; he accepted that, to Skylar, and Jesse, and Walt Jr., and Marie, and Gretchen, and Elliot, and Charlie Rose, and the rest of the world, he was Heisenberg. It was so brilliant because Walt's redemption came from the fact that he was redeemed to himself, and only himself.
