So I think this book is to work with a more intuitive method of type or assimilated the lessons of the NHK. I have not tested these methods to the Japanese, but for other languages (German Basic beginner, false beginner Spanish) and I did not let go. With such methods, it builds up grammar and vocabulary both by not practicing about 20 minutes a day texts on everyday life and progress are enormous (short, we made lots of phrases, increasingly complicated over the lessons without it seems insurmountable when there is first the hardest: writing). That's why I think "Japanese manga" requires this kind of supplement given its grammatical approach.
In conclusion, I would say that it is well structured but free her grammatical approach can demotivate beginners. To overcome this, it is better to work this method with another, more intuitive, in parallel. Anyway, that's what I'll do to not let go this time. ^^