I bought this book for my son a few months before his 12th birthday when he was entering 6th grade. My husband and I read the book and then gave it to our to read it before we discussed it.
I was a little scared of introducing the topic to my son, but by the end of the book I really thought it was posititive and age-appropriate. It focuses a lot on self-respect. In fact, one part talks about when you watch a suggestive tv show or something that makes you feel "dirty" it is your conscience telling you that the behavior is not God-pleasing, and that although your body is normal + natural, it is also private. The book has a short section toward the end about how to deal with inappropriate touching, which is important as my son is involved increasingly in sports and activites away from home.
The book also provides need-to-know detail on the biology of sex. (No gory details!) It talks about changes a 10-12 year old might notice on his own body, about those wierd feelings he may get around a special girl, about eggs + sperm, and how a baby grows in mom's uterus. But it does not mention how males and females "fit" together and steers clear from any "sex is fun" language.
These books are part of a series; there are also books for young teens and older teens. From the reviews I've read, the books for older teens talk a more about dating, what you might find on the internet, sexual deviance, etc.
My overall opinion is that the book was not too much but what a 6th grader needs to know!