Hawking's "A Brief History of Time" is just that - a brief overview of the current understanding of the universe, and some current theories about how it works and how it began.

I found Hawking's use of analogies very helpful in understanding topics, but few things are thoroughly explained. This left me wanting to know more about the things I did understand, and lacking details that might have helped me comprehend things I couldn't.

Still, it is "a BRIEF history of time", and it serves it purpose well - giving an overview to the layman.