Questions about the universe have intrigued intelligent individuals throughout human existence. Luckily for our time, these questions are no longer confined to the realm of philosophy and speculation. Science has come a long way and may now provide basic answers to these questions. Unluckily, answers given by science are usually too technical to be understood by anyone but a small population of experts. This created a need for simplified texts targeted to the general population. Of course those texts can't wish to provide more than a general appreciation of modern scientific theories making many of them rather superficial. On the other hand, delving in the details would do nothing but put off most readers. Achieving balance between clarity and detail is therefore the hallmark of a good general science book.
This book by Stephen Hawking is certainly one of the most remarkable books in this category; definitely a classic! It is informative, clear, easy to follow and a whole lot of fun to read. The book sacrifices detail for simplicity making it ideal for people with little or no background. Nevertheless, there is enough detail to keep the more informed reader interested.
The authors' goal of making the book as 'brief' as possible came with heavy sacrifices. First: some topics needed more explanation to make them accessible to the uninitiated reader. Second: many interesting topics related to quantum mechanics and string theory were not mentioned. I would have preferred if they opted for writing 'a more detailed' history of time rather than 'a briefer' one. That said, the books still accomplishes a lot for its size and the minor amount of time one has to spend to get through it.
BOTTOM LINE: If you are looking for a first book on the implications of modern physics on our understanding of the universe, I can't recommend this one more. If you have read similar books in the last five years, I can't see much that this book can offer.