Impatient Optimist: Bill Gates in His Own Words is a loosely-organized collection of brief quotations from Bill Gates. The quality of some of the things Gates has to say salvages the book itself, which is altogether too brief and casually-arranged. By comparison, Janet Lowe's "Bill Gates Speaks" is substantially longer and more engaging, though it happens to be older (and thus doesn't contain some of Gates's more recent observations). All told, the book is so light on actual content that it's not especially taxing on the mind -- which may be a benefit or a drawback, depending on one's perspective. It's certainly not canonical to understanding Gates and the way he thinks, but since he has many intelligent things to say, it's not a dud, either.
Verdict: Good for light reading, but far from an authoritative collection of Gates quotations