I have read a number of books on how the universe began, eg Brian Greens The Elegant Universe, Hawkins Grand Design, and those have been excellent in explaining the mind boggling nature of how the big bang happened. This book covers some of the same ground but it does it in a way that makes it easier to retain the knowledge - I think the writing style, and the way it sets out to answer key questions really helps. If I had to choose between the 3 I would get this one, but dont let that stop you getting all 3.
3!