Hawking is undoubtedly a very brilliant man, but I’ve yet to read a book he’s written and like it. His more technical material is, no surprise at all, far too advanced for me: I know; I’ve looked; I’ve been very puzzled. A Brief History of Time, on the other hand, goes much too far in the opposite direction. While the facts it delivers may be remarkable, it does not seem to so much as attempt to make the reader understand how they are known, and I am left with a sense that I am supposed to swallow what Hawking has to say ex cathedra. This is bad in any book of learning; it is inimical to good science.
It’s not a terrible book by any stretch of the imagination; it certainly has interesting things to say; and it is certainly accessible. Nevertheless, there are many superior books on cosmology accessible to the layman, that actually tell you about the science and not merely the scientific facts.