Not only is the in game documentation sadly inadequate, but it cannot be accessed at certain moments (like when discussing matters with other leaders and you want to know what the heck they are talking about). I don't know why so many new aspects of the game were left so vague in the in game descriptions.
I bought the game on release day, but I was unable to install it until much later. Having a book to thumb through would have made that day go by much easier and would have prepared me for the new features without going through the dumb (and boring - the AI was a push-over) tutorial.