This is a helpful, and very readable, supplement to van de Lagemaat's Theory of Knowledge and works best as a student text. I use both the Bastian and van de Lagemaat texts for my lesson planning and activities.
Since there have been changes to the TOK curriculum, I'm eager to get my hands on the newer edition to see how these changes have been incorporated. All IB teachers should have this text on their shelves as a resource to help them understand how TOK weaves each part of the IB program together.