This is book one of John Piper's 'The Swans are not Silent' series, which are brief biographical sketches from Church history. In this book, as the title shows, Piper focused on Augustine, Luther, and Calvin. The common theme from their lives was their hope, understanding, and proclaiming of the message of God's sovereign grace and the joy that follows this great truth of theology.
None of these biographies are in-depth. All of them have a particular Piperesque slant to their story. As Piper tries to capture the highlights of their lives, he also labors to show how each life uniquely celebrates an aspect of the doctrines of the sovereignty of God, sovereign joy, the majesty of God's Word, and what that should mean for Christians today. As such, these would serve anyone well who is trying to get acquainted with their lives and why it matters that we know about them. Therefore the book seems to be half biography and half application... and since it is Piper pointing us to application, I would say that is a good thing indeed.
In a recent church history series at The Harbor we spoke on each of these men's lives as well as the lives of Athanasius and Jonathan Edwards. You can listen to those messages here.