The explanations are very easy to read and understand. The author put a lot of effort to help the reader understand the material.
Thanks to this book, I could understand topics that I didn't understand very well. It's also helpful for Rails development.
There's a lot of sample code in this book, and I think it's very easy to understand because Junichi shows you what's wrong with the code at first.
The author always keeps his readers in his mind. The book made me feel like I was listening to him give a speech at a conference.
To sum it up, if you write code as a profession, this is a book you should have to educate yourself in Ruby.
All beginners and intermediate programmers have no need to hesitate over buying this book. If you're going to write Ruby code as a profession in the future, it would be a very good investment to buy such a practical and easy-to-understand book.