A Brief History of Time, by Stephen Hawking, is on the list of great books not as a literary masterpiece but as one of the Times Literary Supplement's Most Infuential Books Since the War. Of course that's completely accurate; it is one of the best selling popular science books ever, spawning illustrated versions, audio versions, reader's companions, while selling millions and millions (literally) of copies.
It's easy to understand why it is so popular. It's not long, and therefore not intimidating. There are no equations. Hawking promises right up front to address the most basic questions of human existence, and he does, although no definite answers about the nature of God are, alas, available.
Almost twenty years after publication, A Brief History is no longer cutting edge. Observation has verified many predictions and theories about Black Holes and the Big Bang and moved on to bigger (or smaller) things. That doesn't make the material less fascinating. The great gift of this book isn't that it explains advanced theories about the evolution of the universe in simple language (although it does). It's that Hawking manages to make material that is inherently removed from everyday life seem relevant. We want to know about Black Holes because they're cool. We want to know why time runs forward and where the universe came from because, damn it, what the hell was God about, anyhow, and why didn't he do a better job? This sense of wonder and curiously was once the property of each of us - we just grew out of it. Hawking evokes that wonder.
His curious little gossipy asides about his colleagues make nice bonus material.
He evoked more frustration in me, personally, than wonder. I was already familiar with the material. This allowed me to dwell more on those universal questions than was healthy. Why DOES the universe exist? And why in hell can't stupid people understand that God, if it did exist, would not be subject to the flow of time but must exist outside the universe? I used to argue on religion boards for fun, and it's hard to shake off some of those habits. My teeth still tend to meet and clench during certain theological discussions. And don't try to talk to me about intelligent design. I was all over this intelligent design thing before it became fashionable, you johnny-come-laties.