Douglas Q. Adams
1 Good and Concise
This is a good book for the person who has some knewledge of the language and wants to learn more about the general aspects of grammar, it consists just in the necessary rules, it isn't a conversational or a deeper grammatical treatise.
The only objection I have to it is that still uses the old orthography prior to the '80s reform (three accents, two breathings), but if you know how to make the right changes (just one accent, the acute, no accent in the monosylables, except as a diachritic, no breathings) there will be no problem at all.
For that price, a very good adquisition.
2 Not for beginners
It's an excellent book but would not be useful as a beginner's introduction to the language. It's directed at someone who has some knowledge of Greek and wants to understand more about the structure of the language. It's easier to follow for a person who has studied Indo-European languages, such as Latin or German, with noun inflections and verb changes.
3 Good for the price
The book is not an extensive study of modern greek grammar; as it says in the title, this book contians the essentials. Look for another grammar book if you're looking for a comprehensive guide. With that said, the book is an excellent tool to use as a quick reference. Well-organized and succint. For the price, it's a good book to add to your library.