My daughter is 5 and doesn't usually have the attention to listen to a chapter book (other than this and the Wizard of Oz) but she asks for this one repeatedly. Something in the story has grabbed her imagination. She says, "it's fun and scary and funny at the same time." The scary parts aren't too scary and she likes that Nim helps the adults and the bad guys don't win. This is a great book. Not too simplistic because it grabbed my imagination, too.