This book is the perfect example of how a book can be written for a younger audience, but still hold entertainment and meaning for adult readers. I really, thoroughly enjoyed this book. It was suspenseful without being (too) contrived or corny. The characters were interesting and unique, yet believable, and the story was truly touching. I thought the author did an excellent job portraying the mindset of middle school-age children, especially in that they didn't all think and act the same, or have the same maturity level.
Also, I don't know if other older readers found the ending predictable, but I was genuinely surprised, and even got a little choked up. Overall, a great read for any age.