This version of The Phantom of the Opera is adapted by Kate McMullan. It's part of a series called Bullseye Chillers, basically simplified versions of classic horror novels for children to read. My guess on the age level of reading for this book would be anywhere from 9 to 14, this also depends on the personal reading level of the child, advanced readers may read this book at an earlier age.
This is a pretty good simplified version of Phantom. Basically it stays pretty true to Leroux's novel. The novel is told from Erik's point of view, and for a 95 page novel with extremely large print and illustrations there is a lot of information packed into it about the phantom. There is detail about his life prior to the Paris Opera House, and there is also an emphasis on his feelings, which to me as a phan is very important.
This is a great book for younger readers to be introduced to phantom with, when I eventually have kids I can assure you they will be reading this, although knowing me they will be clutching a Leroux novel while sleeping in their cribs. This book is worth owning for phantom book collectors and phans hoping to introduce a younger child to Phantom. It's also very reasonably priced through amazon.