I'm using this book for a graduate course in probability for political science, and I have been very disappointed with it. The main problem is that it skips steps involved in problems and then tells you that "obviously" or "clearly" or "intuitively" the solution to the problem follows. For example, my professor has had to distribute his own detailed explanations of sample problems in the book, which have been much clearer (and longer) than what the book offers. If math is not intuitive for you or your quantitative skills are rusty, this book does not give you the kind of step-by-step guidance you'll need.