This book is suitable for advanced learners, and those who wanted to study, review and learn advanced-level grammar found in newspapers, professional journals, technical/business/legal documents, academic papers, and literature! It contains all the Key Sentences, Formations, Example Sentences, detailed notes, explanations, and other infos you can't even find online! The only downside I can think of is that this book is a bit expensive. Be warned, those grammar in this book are uncommon, so if you want to study, learn and review the advanced grammar, this book is definitely for you!
If you already have beginner and intermediate one, and still want to pursue N2 and N1, then having this one is not a problem. Can be used as solely as it is for reference on JLPT. Preparing you more than enough. The vocabs are 5 times harder compared to beginner and intermediate one, so beware.