This is a super series! We love it. Each Friday I give my sons an oral test on the definitions. I read a definition and they tell me the vocab word. I also use it for spelling. We go through the list until they can spell each word correctly. I would recommend this series very highly. You won't be disappointed.
The words taught and the format are great. The selected readings are not always what I would choose for subject matter, but they do cover the vocabulary well. The biggest thing I'd like to see with this book is to have the answers included in the text--either right in the book, which would be ideal, or shrink-wrapped with the text.