I bought this for my grandkids, but only one is old enough to appreciate it. An eight year old, who got about halfway through before she bogged down. I'd recommend it for 10 to 12 year olds unless they are especially good readers.
It is extremely well written and covers complex subjects in an understandable manner. The way the author covered the science impressed me, a retired engineer. Feynman is not only the "great explainer." So is the author. Bravo!