I really enjoyed this book. I would say it is intended for readers about age 8 and up. Each sign of the Zodiac is examined in scientific terms (what are the prominent stars in it, for example) but it also tells the mythological story or stories which grew up around the constellation.
An additional feature of the book which is very appealing are the illustrations. Christina Balit has created stunning illustrations with silver foil stars in the correct positions overlying the more evocative illustration of each sign. So when you look at Taurus; for example, you see the mighty bull. But tilt the book and the light catches the silvery stars in their correct positions. I love it!