Some reasons I believe this book is a good choice for middle to upper elementary readers is because the content is something they can identify with. In this specific book (it is a part of a series), Peter is the main character. During the novel, he faces many life changes. For example, his family moves to a new town and a new baby joins the family. Children reading this book may be able to relate to the situations that Peter faces and some may be his age. Peter also has a little brother, Fudge, who trouble seems to follow wherever he goes. This annoys Peter, but makes for many comical moments in Superfudge.
Another reason I believe Superfudge is a good choice for young readers is because the language and sentence structure would be easy for them to understand. The words used in the book are fairly common and would be easily recognizable for many children.
Family, friendship, and life changing events are all found in Judy Blume's novel Superfudge. Even if all readers do not identify with the characters, I believe they would still get a few laughs and enjoy this book. Superfudge is light-hearted and full of surprises, and I would also recommend the other books in this series.