What the book does, really, is revive the narrative of the Psalms. Wright provides just a bit of historical backdrop for the Psalms in the beginning--they were first arranged during the Babylonian exile, a fact that will turn out to be quite significant--and then he goes on to outline the major themes of the Psalms. (I assure you they are very compelling themes, along the lines of how past, present, and future intersect, and also how God is at work in, and how he views, the Creation--that kind of delightful stuff!) Then, in the main body of the book, all kinds of marvelous connections are made between the Psalms and Genesis, the Psalms and the prophets, and the Psalms and the New Testament. Finally, in the last chapter, Wright gifts the reader with some personal vignettes of his own life with the Psalms. These are immensely readable if you are at all an NT Wright disciple, which, as you may have gathered, I am.
One of my main takeaways is--and I leave this for your consideration whether you end up reading the book or not--that we should shape our lives around God's narrative and not try to shape God's narrative around our lives. The Psalms provide us with one of the best ways to do so. They allow us to voice every imaginable emotion and human experience--doubt, despair, jealousy, malaise, triumph, joy--and yet steer us firmly in the path of the Great Tradition, putting us in touch with past pilgrims rather than putting us out in no-man's-land with our own solutions or solutions from Post-enlightenment Western ideology.
Wright makes a convincing case for having the Psalms as the very backbone of worship, both personally and collectively, and he recommends reading privately the entire book of Psalms every month or perhaps two months, and, in public, singing, reading, and praying the Psalms instead of using some cheap modern-day worship pastiche. Examples of the cheap parody worship are
1) Fundamentalist/Calvinist hobbyhorses and sentiments (Rubbish like: it's all gonna burn; the world is going to hell in a handbasket; God created the world knowing that most people and certainly all matter will not be redeemed; for all intents and purposes God is cantankerous and distant when it comes to his dealing with the world).
2) contemporary church music, a phenomenon that, while it has seen a prolific output in new compositions in the last few decades, is often sadly lacking in themes from Psalms.
Instead, we should return to the Psalms! I leave you with two snippets from two legends of the faith. CS Lewis said Psalm 19 is the greatest piece of poetry ever composed. Billy Graham read 5 Psalms every day and 1 chapter of Proverbs every day, thus getting through both books every month. He said the Proverbs helped him get along with people and the Psalms helped him get along with God.