This book is excellent. It is a whistlestop tour through the history of Catholic philosophy and covers all the important thinkers. The first few chapters on the differences between theists and non-theists are the best of the book and clearly lay out all the important issues. Given the current leave of the debate between theists and anti-theists, they relay the ground rules. I say anti-theists since most non-theists who are not anti-theists are aware of the points already.
Well I think the first few chapters of the book are the best this is not to say that the later chapters are not also superb. To sum up I think this book is a good introduction and summary for both the lay and informed reader alike.