I had lived in Korea for a few months a few months before buying this book, and I already knew a (tiny) bit of Korean. But I wanted to learn more, so I was looking for a well-structured and challenging Korean textbook. There are many books for beginners, with cultural stuff, pictures and everything, but these books don't really help if you want to improve a lot on the long term.
So I bought this book, and it's great. It's divided into 24 chapters, each chapter explaining an important grammar point. In each chapter, you'll get a few pages that explain the grammar use, its use, and structure. Then you have, for each chapter between 5 and 10 application exercices that cover the material of the chapter. The textbook also has a vocabulary list for each chapter, so that you can practice using new grammar and new words. The book is straight to the point, and you'll see a noticeable improvement in your grammar skills.
I'm giving this book a 5* rating, because it's an absolute must-buy. I haven't seen any similar books for learners of intermediate levels. However, it's not exactly perfect :
- Every now and then, I noticed what seem to be typos, especially in the Korean texts. It's a bit confusing, because the language can be challenging enough, so these typos just add to the confusion.
- The exercices are a bit repetitive. There are two main types of exercices, and they only require you to modify existing sentences, by taking into account the new grammar rule. So it can be a bit annoying after a while, because exercices seem a bit easy sometimes.
Finally, and I can't stress this enough: this book alone is not enough. It is a grammar book, and you will need to have other ways to practice your Korean if you want to improve. So this book works best if you talk with Korean friends, use Internet websites to learn Korean, watch Korean dramas/movies, try to read other stuff in Korean, learn vocabulary (through flashcards, dictionaries or whatever works...). But this is not the due to the book being bad or anything, it's just how any language works : if you want to really learn it, you'll have to write, read, speak, listen to it and learn the vocabulary.
So, this book is probably hands-down the best book on the market for intermediate speakers. It's both accessible and thorough, and it's worth the money. You'll go through dozens and dozens of expressions, structures and rules, and will be able to expand your ability to understand and communicate in Korean. But, to make best use of this book, complement it with other ways to learn Korean.