This book really is for the true beginner in international taxation. If you are a professional, it is probably not the source you are looking for. However, for a person who does not have knowledge in this field or has never practiced, I think it will be a brilliant book to read.
The book in itself is very well structured and very clearly written. I use it a primer for my young associates when they join my firm and have been very pleased with what they learn from it. Once they have read and "metabolized" this book, they are ready to get started, and as far as I know, there is no other work to pick up where this primer leaves the subject.
In other words, this is "only" a primer, but as far as primers go, it is a brilliant one. Buy it if you are a beginner or if you have lots of beginners in your firm.