This book is the best introduction to the issues involving the Septuagint that I have run across. Unfortunately, it was written in the Sixties, before the wealth of information provided by the Dead Sea Scrolls began to be considered by the community of biblical scholars. And the DSS rewrite the story of the Septuagint. Unfortunately, the lack of another comprehensive introduction keep this book on the required reading list. Just don't think your understanding of the LXX is sufficient after reading this book. You will still need to delve into the writings of Emmanuel Tov and others, though they are not intended for the beginner.