The course is pretty solid in its method: it mixes the basic information needed to survive in Germany (that is, basic phrases, greetings, politeness, buying stuff, culture, and the like) with grammar explanations, following a steady pace, taking care to show one thing at a time. The way they handle vocabulary may not be to everyone's taste though: it starts out very thorough with translating new vocabulary, but become less and less as you progress units. If you're the type that likes a challenge, or was already acquainted with language (for example, through Duolingo, like I was), you may like this, as it makes you try and infer the meaning of the "non-critical" vocabulary in the used texts and audio, or test the vocabulary you already before. Otherwise, you may find this book a bit frustrating.
Please note this is NOT a complete course of German: it does not teach future tense at all, for example. But it is still a good introduction to the language, and it may be supplemented through other sources (the Teach Yourself Series has other books such as Improve Your German, Further German and Enjoy German, for example). If you're looking for a book with a complete course though, you may need to look elsewhere.