This book is an excellent reference guide for learning Urdu. The grammar coverage is in incredible detail - although it can get quite technical for a non grammarian.
However, this said - the book does give plentiful scope for different types of students - i.e. those seeking to learn via the more grammar based approach and those seeking a book with plentiful examples that they can use as a complementary resource to audio based resources. I have used the book in the latter sense as Urdu is my mother tongue but I make plenty of mistakes.
The amount of content and research that has gone into this work makes the price worth every penny.