My fourth grade daughter with ADHD read this book easily by herself. It took a chapter or two to grab her interest, but I was glad she stuck with the story. She gets teased in school for minor differences in her appearance from the ridiculous standards of beauty set by TV and movies, like they are in every generation. This book might help her love herself a little more.
Besides, she adores unicorns, and like she said, "How can you go wrong with a unicorn in a story"
I think the language in the book is a bit stiff and formal for school age children--they're accustomed to slang, half sentences, contractions, and shortcut speech, but maybe some formality isn't always a bad thing.