I read Stephen Hawking's original A Brief History of Time almost ten years ago and thought enough of it that I bought a copy. In that volume Hawking attempts to explain in reasonably simple language what science knows about the history of the universe, the origins of it, and what we know about the universe today and potentially its future. Fascinating.
A Briefer History of Time is a an updated version of the original book. The content has been slimmed down a bit to give simpler explanations of the scientific concepts, but Hawking has also added information to become up to date with scientific advances since the original publication.
The result is the book is still rather confusing because these are still difficult science concepts that are way beyond my experience and knowledge, but Hawking does an excellent job putting these concepts in as simple a manner as possible. They are just difficult to grasp to someone without a science background.
Still, this is an interesting book and one which when taken with other science books will hopefully have enough material stick so that I'll better remember and grasp other concepts.
A note about another "Hawking" book. The Theory of Everything: The Origin and Fate of the Universe is not supported by Hawking. He wrote the essays years ago and the text has appeared in other books. His official website disavows The Theory of Everything because Hawking was not involved in the publication and does not approve of it.