It is foolish to think you can learn to speak any language without real interaction with teachers or native speakers, so taking live classes really becomes a necessity at some point, but using this audiobook as a complimentary way of practicing, improving vocabulary and learning grammatical points is a great way to improve your Japanese or at least learn expressions you can use to get you stated. The one thing it lacks is a chance for the listener to practice what they have learned, since mostly you listen, and the main interaction you get is repeating single words or short expressions. The actors are pleasant to listen to, the material is engaging and very rich in Japanese culture and applications for the material learned. I am very happy to have found it to assist me in my learning and will purchase other books from the same series. I wish there was a clear way to determine the order in which the publisher expects us to use the books in the series, since they seem to be randomly numbered at times. This one is definitely a keeper though.
This system is great as listening and speaking practice for those who only need some basics for tourism. The work is well presented, it's fun to follow and quite challenging in good way. I missed having written materials, and real explanations of the grammar. My fear is that without those you end up like a parrot, able to repeat things, but without much ability to create your own much past what you have been repeating. Also completely unable to read anything.
The method presents itself that way, and it does what its system suggests very well.
I gave it a 4 because, though I don't believe it should be your only resource if you really want to learn the language, it most certainly is an incredibly helpful one.