I nearly rated this one higher than it's grammar equivalent because it at least does no harm. Then I remembered that doesn't exactly help you learn vocabulary and the impulse faded.
Similar to other books in this series, it consists of 8 weeks of lessons, 6 lesson a week + a review quiz on the seventh day. The reason I think it isn't helpful is because each "lesson" consists of a list of words, each with a (very) brief example or two, and a translation of the example(s) into English (and Korean and Chinese). Similar to the grammar book, you have to divine the meaning of the word from the example. The problem was that someone masterfully translated the examples into English, often using idiomatic language, rather than give a translation that best help you understand the meaning of the word.
There were also just too many damn words. Maybe the intention was to review vocabulary you already had a good grasp on? Rather than learn new vocabulary? But I can't cram 30-50 new words into my head every day and hold down a job. Especially when they're organized thematically or by kanji, so it's 45 new adverbs, or 30 words based on 4 different body part kanji.