This book has various mistakes (mostly in regards to romanization) and is very difficult to navigate seeing as it does not clearly define chapters and sections. I also really dislike how it doesn't use kanji anywhere near as often as it should.
However, it's a good supplement (as designated in the title) and works fantastically as a quick reference when reviewing grammar. For the price you can get it used (around $5USD including shipping) it's not a bad resource to have.