I found this book very frustrating.
In the first place, Krauss spends far too much time God-bashing, instead of just sticking to the science. Fine, he doesn't believe that God created the universe, but there's absolutely no good reason to even bring it into a discussion of how our universe has been created from nothing.
In any case, ultimately, his arguments seem no better than a belief in a supreme being as creator. Krauss waves his hands and tells us that most of the universe consists of "Dark Matter" (fairly easy to believe, as it is simply matter that we can't detect with current instruments), and "Dark Energy" (a seriously kludgy substance that exists purely to make physical theory match observed reality, via the "Cosmological Constant"). How is it that if we believe in God, we're credulous cretins, but if we believe in Dark Energy we're "scientists"?
He even had the nerve to introduce Occam's Razor
. If we are to use the Razor, perhaps we shouldn't jump so blindly on the Cosmological Constant bandwagon — a part of Einstein's General Relativity that he seriously regretted, and considered an error.
Now, my knowledge and understanding of physics is probably about as good as it gets for someone without a degree in physics, and I didn't have too much trouble following the science in the book — but it was hard enough that it can hardly be considered as being a book for the layman (that is, the science is far harder than A Brief History of Time). Perhaps he could have provided arguments that would convince me, but if so, the book contains too little physics to convince anyone of his case, and too much for most readers to follow.