My children (2 and 3) love this book. Much of it is over their heads, but they learn a little more each time they read through it. I was expecting the book to be about specific animals, but found that it covers animal groups (mammals, reptiles, etc.). I'm fine with that. The kids love learning the differences in mammals and birds!
I did not give this book 5 stars because I felt it was disjointed in the terminology. It goes from mammals, reptiles, and amphibians to "creepy-crawlies" and "water life." I wish they would keep the same level of technicality throughout.
Overall, this is a good book! It has lots of information for your little one to pour over.