I think that this book is really only going to be something special to kids who know very little about the solar system. My kindergarten aged nephew knew a bit; he told me that Earth was the third planet from the sun, he knew the planets furthest from the sun are the coldest, and he knew that Wall-e is a rover, similar to the Mars rovers pictured in this book. The problem was, the book was a little too long to hold his interest the whole time. We read this in Kindle format, so maybe if we would have had the bigger pictures afforded by paper books, he'd have had a longer attention span.
My third grade niece already knew most of the information presented in the book, so while she listened to it, I don't think that she really learned anything particularly new. A few things were new, but most of the book was solar system basics.
I guess, that as Earth is in relation to the sun, a kid just has to be in the sweet-spot educationally/developmentally speaking in order get the most from this book. First or second grade, perhaps? Also, go paper with this one.