This book is of an excellent nature. It treats all grammatical concepts in great detail. Topics covered include the sound and writing systems, the morphology (the structure of the words and their possible inflections) and the syntax (the way the words are arranged in a sentence).
As it is a comprehensive grammar of the modern language, you should be prepared for a lot of linguistic terminology. However, if terminology such as "periphrastic", "oxytone" and "clitic pronoun" seem difficult they need not be because there is a glossary of linguistic terms at the back. Though if I had to make one improvement to the book it would be in the glossary, where a number of grammatical words would need a bit more explanation to make them fully understandable and complete.
Having said that, this book was designed for advanced students of Greek or for linguists with an avid interest in the language or languages in general. If you are a beginner to the language and/or have had little formal language learning experience, you would be best advised to buy the "Essential Course in Modern Greek Grammar".
Its comprehensive and insightful treatment of Modern Greek grammar makes this the best book on the subject and I have no hesitation in recommending it.