just played with an American friend who was learning for the first time yesterday. The winds are by far the most annoying part. Not only is the order of them different than what most people are used to (ESWN vs NESW) but the points you get for each depend on what wind you are and this is on top of having to memorize the Chinese characters (although of course some sets number them). Great game but so many little special cases that can make it intimidating to learn.

Don't even get me started on scoring when you are gambling (although the dynamics of who pays who and how much is interesting)