I'm a big fan of Conti & Smith, and ordered a paper version of this book almost as soon as it was available.
If you are a language teacher, or at all interested in how to learn languages better, get and read this book. You will find a lot of your intuitions confirmed, but will also gain a lot of useful and practical information on things you may not have thought much about before.
Why deduct a star? I'm a pretty patient and determined reader when it comes to consuming content in my area of interest. But this book is basically a textbook, and not that well suited to breezing through like a novel. Sometimes I needed to put it down because it was covering familiar ground; it read faster when it introduced a newer line of thought. But I'm glad I finally worked through it all. Highly recommended.