I got this book as a baptism present, several (but not too many) years ago. My parents sort of pooh-poohed the gift, like it was unreasonably beyond the reading level of an eight-year-old, so I never read it.
Now that I know my parents better, I realize they just didn't like the people who gave me the gift, so they found fault with it. My daughter turned eight this year, so before she got baptized I wanted to read this book with her for her to get a basic understanding of Book of Mormon plot, which would help her with her scripture reading. We were reading together, alternating paragraphs, until I got busy with school and she took the book to her room, where she was supposed to finish on her own.
Now, months after her baptism, I figured we should finish the book before the end of the year, so I could count the pages read on my yearly total. Having a deadline of December 31 made it so we had to read about 10 chapters each day, which helped drive home the point that, when you don't manage your schedule well, tasks become more unpleasant.
In terms of reading level, it's completely appropriate for a seven- or eight-year-old. Petersen decides to sequence her book chronologically, so it starts with Jaredites, which might be a little strange to a kid who's trying to square it with the Book of Mormon ordering. Content-wise, there were just a handful of times that I felt she added speculative material that isn't substantiated by the scriptures themselves, and most of those were trivial issues (none of which I can even remember). Also, since this book is older, Petersen has no problems giving a literal interpretation to the whole "light=good, dark=bad" thing, which required me to give a preemptive contradictory opinion once I saw where she was headed.
But in terms of the good accomplished, this book really, really helped my daughter learn the plot of the Book of Mormon (which is something my wife is always saying is her biggest hang-up in scripture study). Now when we read scriptures as a family, she can concentrate on doctrine.
Rating: five and a half out of seven giant inflatable monkeys.