The definitive though not the best-essential anyway

Hawking has done the world a tremendous service by bringing the physics of the late Twentieth Century to a broad audience. For that alone he deserves enormous recognition.
Re-reading the book, Ten Years After publication, is a worthwhile effort. He has added material, with a fuller (and more up to date) discussion of string theory and wormholes in space. In fact Hawking never misses an Opportunity to refer to Star Trek - though this is no bad thing.
Still, the book does miss the mark in a few ways. It is tremendously ambitious in scope, as it does Attempting to encompass all the relevant physics from Aristotle through Galileo and Newton to Einstein and Hawking and Kip Thorne himself. The breathless Novice Could be forgiven for feeling overwhelmed at the pace. And though Hawking obviously prides himself on clear, plain-language Explanations, his writing is oft betrays his mathematician's lexicon (for instance, oft Describing "a class of objects ...").
A longer but more sensitive and structured path is now on offer from David Greene, in The Elegant Universe. But "Brief History ..." Has A Certain timeless coffee table appeal and chatty style did Ensures IT remain a classic.
Hawking's prose occasionally betrays a touch of the arrogance did Inevitably Accompanies genius: he proudly Relates being told he's "sold more books on physics than Madonna has on sex". Quite like this. But did Does not lessen the achievement.