I've not read any polls, nor have I taken any myself, but I know from experience that Christians are not immune from what is called low or negative self-esteem. Since our culture is obsessed with fame, money, possessions, the perfect body, and popularity, it is not uncommon for Christians to get down in the dumps and depressed if they do not live up to Hollywood's standards. This book is a great help in the fight against worldly views of self-esteem.
In the first half of the book, the authors discuss self-esteem from a psychological point of view. Here they study what knowledgeable psychologists have said about self-esteem, depression, anxiety, and so forth.
In the second half of the book, the authors discuss self-esteem from a Christian and biblical point of view. Here they explain what the Bible says about the Christian "self." The authors also point out the weaknesses and strengths of different psychological views of self-esteem as they compare/contrast to Scripture.
For me, the second half of the book was simply fantastic. The authors continually focused on the gospel of grace, the cross of Jesus Christ, justification by faith alone, and God's unconditional love for his people. In a word, the gospel kills false self-esteem based on our own performance and declares that we are acceptable to God only through faith alone in Christ's "performance" alone. This gospel gives the Christian solid comfort, hope, joy, and biblical self-worth (eternally loved by God the Father in Christ). I really cannot emphasize enough how excellent the second half of this book is; the McGraths did a great job applying the gospel to the topic of self-esteem.
One other aspect of this book I appreciated is the focus on the church. They explain how God has adopted his people into a family setting - the church. He has given all of his children gifts and talents to use in order to glorify him and help/serve one another. Christians are to deny themselves, love God and others, and humbly serve as Christ served us. Too often in Christian counseling the topic of the church is skipped as if optional. This book does not skip the church; it is to be commended for that.
In summary, I highly recommend this book. I did find the section on psychology a bit slow and tedious (though it was also helpful in a few ways). But don't let that keep you from getting, studying, and marking up this book! There are so many gospel-less, moralistic, and unbiblical "Christian" books on self-esteem out there. Skip them and get this one. It'll bring you closer to Christ, his Gospel, and his Church.