I bought this book on the strength that it is by Kunihiko Kasahara. I am an admirer of his works and have attempted to collect all books by him.
There is a lot of mathematics involve so for those who like to combine mathematics and origami, this is a good book to add to your collection. If you are just interested in origami and not mathematics, perhaps, you might consider browsing it at your local book stores before deciding.
The models within are not really that amazing, in fact rather simple. These simple models are being used to illustrate the mathematics involved in the folding of the models.
The 5 platonic solids (tetrahedron, cube, octahedron, dodecahedron, icosahedron) are introduced here, the mathematics involved and how to fold it. They are very attractive to fold if the right colours are chosen. Boxes, stars, tangrams and other geometric solids are included. Most of these can be used for decorations other than studying the mathematics involve.
Whether you think this book is worth getting will depend a lot on your interest.