Yancey's approach to this work was essentially based on the following question:
He then considers various aspects of Jesus as put forth in the New Testament gospels (i.e. the books of Matthew, Mark, Luke, and John), whether they be from the point of view of those who were "on the scene" or statements/actions of Jesus himself. Given the title of this book, you can imagine that Yancey comes from a background where he has had to work hard to set aside various modern interpretations and pictures of who Jesus was and what he was like to reclaim the Jesus of the Bible.
My take is that this work is essentially "bread-and-butter" theology. I do not think that, what I would term "active" Christians (those who attend church regularly and study the Bible regularly), will read anything that they do not already know. However, more casual Christians, seeker-type Christians, or those who have never really spent time studying Jesus, will find lots of things that may upset or reform their view of who Jesus was. The next Yancey book that I have on my shelf to read is Disappointment with God. I greatly look forward to this one.