We finished the second season of Deadwood. What a great series! All of the characters are fascinating, and almost all of them live in that ambiguous zone between good and evil. Powers Boothe's character (Cy Tolliver) is probably the only truly despicable character; it's interesting that he is playing an evil character on 24 this season as well.
Without having done a careful analysis, it feels like this season was mostly centered around Al Swearengen: the end of the season finishes with a shot of him. The first season felt like it was more about Seth Bullock.