This book would be okay if were called a dictionary of homophones, which it is, instead of a dictionary of easily confused words, which it isn't. I wouldn't have bought it if I hadn't been duped by the title.
For example, does anyone really mix up inn and in? Or son and sun? I don't think so. But this book will explain the difference.
On the other hand, there are no entries for eager and anxious because they don't sound alike, although people mix them up all the time.