I was going to buy this as a gift for my stepdad, inevitably playing with my family which is a group of four, but I saw numerous people posting that three players was really what you should try to play it with. I read various reviews and even watched a video on the game, and I honestly don't see why it would be any worse to play with four players. Why do you think it might be worse with four instead of three?
Well my guess is that since there are only 7 of each Outlaw card there can be a bit hard to get the 3 needed to play the first set. Otherwise I don't see any problem.