This is vintage Piper. It serves as a condensed introduction to his larger work: Desiring God. By-in-large, the book is quite good. As always, Piper teaches through Scripture some very profound Biblical truths. He is not quite clear at a few places in explaining things, and a couple of the chapters are rather short and offer little. Overall, the work is good, and is a nice primer for Desiring God.
This short book gives the reality of what living the Christian life is all about - the joy of knowing Jesus. The understanding and fulfillment of this brings us into a life of love and grace rather than laws and disciplines. You'll have to read it for yourself - there is pleasure in serving God!