Firstly, the good points. This is as accessible a work as I have ever read about philosophy and theology. Difficult concepts are very well explained and demonstrated, and theories linked together. I consider myself reasonably well read, but until I read this book there was many philosophical concepts I barely understood, and some I was entirely ignorant of. It covers the full spectrum of issues surrounding the idea of God - What do we mean by `God', arguments for/against existence, his attributes, effects of scientific discovery on our understanding of God, miracles and spirituality, etc. In short, it's pretty comprehensive. Had Richard Dawkins read a couple of small chapters in this book, he could have saved his blushes on a few occasions. Conversely, I doubt many churchgoers are aware 10% of what is in this book. In fact, you could probably say that about 99% of all people are completely unaware of even some of the basic concepts noted in this book (though that hasn't stopped people having strong opinions on them!). Considering this largely ignored subject area, the writers do an excellent job or explaining most of the issues in a clear and memorable fashion.
Onto the bad points. Though occasionally Islam, Buddhism, Judaism and a couple of other religions are mentioned throughout the book, it's mostly about Christianity. I would personally liked a little more about the other religions. A couple of the chapters are pretty mind numbing, though this may well be because some of the issues are so dry that even the best explanations cannot shed any light on them. The chapter on the Attributes of God for example, is so dull I couldn't stop myself skimming over it. Maybe it is simply impossible, however, to have an interesting discussion on the subject.
I think if you are interested in the subject, and are looking for a place to start, I can't think of a better book to introduce you to the relevant issues better than this one