The only drawback I found in this book is its lack of mention of transgender or intersex people. This is otherwise a very thorough book. It's got cute little illustrations, but they're usually fairly realistic. At the beginning, it just says that girls and boys can do the same things, but girls and women have a vagina, and boys and men have a penis, and there's other things that are different.
Message
Where babies come from. Also, don't let anybody touch you in a way you don't want them to.