This is one of those "torn between three stars and four" books. I did get a good sense of who Newton was. He was an asshole.
Gleick gets pretty technical. A lot of this book describes Newton's theories, including calculus, in no small amount of detail. I've been frustrated in the past by biographies that didn't go into enough technical detail about the discoveries of various scientists, so this may be a "Careful what you wish for" situation; I've always been shit at calculus, and much of this book flew right over my head.
But it does the job. At under 200 pages it's a snappy read, and I understand Newton and his place in history exactly as well as I want to, so: mission accomplished.