This book is a real gem for me. Its like having one of the schoolbooks used at Hogwarts. This book contains lots of information on the fantasy creatures featured in the world of Harry Potter. Remember the Hippogriff Harry rode in Hagrids class? Find more info on it here. Its a valuable encyclopedia when reading the Potter books. Just look the information up as you read.
I recommend this book for the Potter fans out there. Get both editions too if you want. Enjoy!