The book is a sex-ed book. It has illustrations, but they do not appear to be any worse than what one would get in a heterosexual sex ed course and that is often taught to sixth graders. This class a appears to be for students a couple of years older.
Here is an image that I found. Not to worry, it has been pre-blurred:
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Also it is rather highly rated as several sources including Amazon where it has a 4.8 out of 5 rating:
Amazon.com: This Book Is Gay: 9781492617839: Dawson, Juno, Levithan, David: Books
www.amazon.com
And then there is this. At first I thought that it might be an article from a hater, but this shows how the book teaches rather honestly. This part of the book is on why a gay person should not use steroids to look more masculine as some do:
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