Here's the problem: Context isn't considered in the book's FORMAT; the book gives phrases and idioms in alphabetical order. There are examples of usage given for each entry, but the alphabetical listing is not helpful for students learning new phrases, that is, there is no grouping in context. For example, if you want to learn a set of common phrases used when telephoning, or when you perhaps want to find out how to interrupt someone politely or otherwise, you're out of luck with this book. No way to go to a section on phoning, or conversational guidelines. To use this book, you need to have heard a phrase, memorized it, and want to look it up. It can be a good reference, probably useful for students doing translations.
In short, it's a shelf book, not a book geared for teachers to teach with or students to teach themselves from.