Other reviewers are entirely correct to emphasise that this a textbook for Christians to learn apologetics from, rather than a book addressed to non-Christians. However, it is not *entirely* inappropriate for a non-believer, especially as it's probably the best Christian apologetics book there is. I read it as an atheist and it did a lot towards my conversion. The most important thing I can say about this book -to the Christian and non-Christian alike- is ignore the first chapter. This suggests treating Bible as infallible which to me is irrational, futile and very off-putting. But from the third chapter onwards it is very reasonable and just keeps getting better.
It gives a very detailed account of the case for God, in addition to other central apologetic concerns. It's not exhaustive, there are plenty of other topics that need to be covered, but they can be found elsewhere (look up my listmania list). Yes it's not perfect, there's plenty of things in there I disagree with, but the central argument is solid. Speaking as a philosophy graduate, there aren't any major fallacies- contrary to what other reviewers have exhorted so emotively. If someone thinks they've found a fallacy why don't they spell it out in detail?
Finally, if you're unsure whether to purchase the book a lot of the same material can be read in articles available on Craig's official website. Here he also responds to e-mailed criticisms of his work on a weekly basis.