If you are interested in Elon and his quest for making humanity multiplanetary, this is a great read. It also serves as a great introduction to some of his ventures like Tesla, SpaceX, and SolarCity, but it doesn't go much further than that: an introduction, so if you don't care about Elon himself, I wouldn't bother with this book.
The book is surperbly written, exhaustively reported, and it gives what feels like a definitive take on a man who is in many ways larger than the life of ordinary men, maybe even surpassing the people he is most often compared to, like Steve Jobs and Tony Stark.
The book is light, and never feels dull. If you care about Elon Musk, it's a definite 10/10 recommendation. However, for the casual reader, I give it 6/10.