This is a GREAT book to have as an accompaniment to other lesson books, as a self-learner. It DOES focus more on actual practice and gives the bare minimum in the way of explanations- so, if you're JUST starting to learn the language, you will DEFINITELY need other books that go into more depth with full grammar explanation. A lot of the time, it's difficult to think up things to write as practice when you don't have a teacher to assign you lesson-specific homework. So, think of this thing as a giant book of homework rather than an all-in-one, full German course.
I only gave 4 stars, though, because I've noticed that, for some lessons, the wrong 'Answer Key' is given in the back of the book. Specifically, for example, the answer key for lesson '3-8.' Luckily, I am in contact with multiple native speakers that were willing to check my answers, so the lack of a correct answer key isn't a MASSIVE bother for me... however, if you don't have a German handy, it could be a problem.