I am reading this slim volume right now, and I got the urge to e-mail Costikyan and say good job. But I couldn't find any way to do that. He has a FaceBook page, so that's an easy solution...if you're on FaceBook, but I'm not.
<insert rant about folks who assume everyone is on FaceBook; cite examples of people whose business cards offer no other way to contact them... >
So I'll just post my love here. This book, which is part of a series called 'Playful Thinking', is an attempt to catalog the ways in which uncertainty is important to the design of games of all types. Costikyan makes a strong case for uncertainty being an important part of a great game.
I find this sort of thing exciting, in that it makes you feel like you could design a game. But you don't have to be a game designer to get a lot out of this book; it's a great help in understanding games.