While this series is great for fourth grade and up, this book had a little more human-on-human violence than the others. Freddy is very vicious, so this starts out with more brutal killings than most books. This does, however, serve to highlight Alex's compassion and dislike for killing.
There are four series in my library that I make sure are being held together by whatever means necessary: Horowitz's Stormbreaker, Ally Carter's Gallagher Girls, John Flanagan's Ranger's Apprentice, and Shan's Cirque du Freak. I don't know that I could work in a library that didn't have the complete Stormbreaker series. Just couldn't. I have told my daughters that my personal copy of Secret Weapon must always stay with me; I'll need it to be handing it to people who visit me when I am very old and still thinking I am a school librarian!