Bullock and Star just didn't work that well on a second viewing - they seemed a bit thin on the ground and weren't really carrying it for me. Swearengen and Garrett are pretty good.
Trixie's an irritating 'whore with a heart of gold' stereotype as well. The minor characters are just as great, eg Utter, Farnum, Calamity Jane, and Dan, but they're a pretty sorry lot as well.
It was definitely a great show but I think because it didn't carry on with its setup too well, and really falls apart in season three, it just wasn't in me to watch more than 5-6 eps again. Desperately needed that wind-up feature film that never got made.