Whenever I start up a new game & it turns out I have Sitting Bull as a neighbor I usually restart unless I have really nice land. I cant stand this guy, he's protective & his UB give even more exp to his already strong archers. His UU is a resourceless axe with a bonus against melee, dog soldiers eat swords & axes for breakfast. I dont like to rush early ( unless I'm really boxed in ) but Sitting Bull while not impossible to rush will make you spend 100% more hammers on troops to conquer over a standard civ.
Sitting Bull also seems to spam cities at a incredible pace, if you arent boxed in by SB you soon will be. He's a slowish techer but also doesnt like to trade techs so he makes a horrible trading partner. Only Catherine is worse in making demands, as soon as I hook up a new resource SB is sure to demand it!
The #1 reason why I hate Sitting Bull however is......espionage. Whenever I play a game with him as a neighbor I'm getting my cities water poisoned CONSTANTLY, this guy seems to be put in the game to make the human players miserable.