If you already have a basic grasp of Japanese sentence structure, then this is a good intermediate and comprehensive language book for those who want to extend on their Japanese.
As the exercises progress, they try to incorporate what you've already learnt from previous chapters; however this book would benefit from a little more coverage on particles which can be a very confusing aspect of Japanese. Wa and Ga, potentially 2 of the hardest to master, are only really dealt with properly a bit later on, and in addition to this, I also noticed a few grammatical errors, one of which was in the exercises. I think it is especially important that language books are proof read and edited well before publishing. This was a little disappointing, but on the whole would definately say this book is worth buying; it's a very good student reference.