I think a couple of words are in order in response to the criticism of some of the reviewers of this book.
First off, Wright is most assuredly not teaching any sort of a works based salvation. He simply points out that when Paul speaks against the Judaizers of his day, we can not, as Luther did, project onto them a meaning consistent with that of the Medieval Catholic Church. That is, Luther read Paul struggling with the Judaizer's speaking of the "works of the law" then saw his own struggle with the Church that seemed to place an endless string of hoops to jump through to achieve salvation. He assumed Paul was speaking to him in his situation directly. "The Just shall live by faith" became for Luther a liberating statement. Faith, not works, is how one is justified before God.
However, Wright explores more precisely what it was Paul was up against. What it was, was those who insisted that the things which made the Jews separate from the nations, such as circumcision, food laws, etc. desired to impose these on new Christians as a badge of their membership in the New Covenant. No, Paul says. It is faith, not these works of the law, which mark you out as a true covenant member. If you live in faith, which is of course outwardly exhibited in obedience, then you will be known as a true covenant member. This is most definitely not telling us that through our works we are or even can be justified before God.
Instead, God's justification is really closely tied to his righteousness. Not just righteousness in terms "God is better than us" (though he certainly is) but righteousness in terms of His faithfulness to His covenant. God will justify His people. In fact, in time and history, He has done so in the cross. The cross is very central to Paul's writings.
But, who are God's people? Those who believe the Gospel. What is the Gospel? According to Wright, the gospel Paul preached was not a set of instructions on how one goes about "getting saved," but the gospel was the proclamation of the good news that God had redeemed his people in the cross, that Jesus had rose from the dead, and (this is very central) that Jesus is now the reigning King of kings and Lord of lords. He is the King over all of the universe, so this is a universal message, not confined only or even primarily to the Jewish nation. Those who profess a belief in this are part of the visible covenant people, but the true members will be known by their fruits.
All this is not to say Luther was totally wrong or without merit, and certainly it was not to say the Roman Catholic Church was right. Yes, Wright is a Protestant, the reader from Canada's criticism notwithstanding. The first century Jews just simply did not hold to a works based salvation as many since Luther have supposed. With this in mind, we can not take Luther's interpretation as completely accurate.
Another somewhat soft criticism is that the book is mis-titled, since only the last chapter actually concerns the issue of whether St. Paul was the true founder of Christianity. Admittedly, I had the same initial reaction because this is not something overtly talked about for the majority of the book. However, the entirety of the book outlines the fact that Paul was simply taking the teachings of Jesus as they were to be interpreted for those in Paul's time - and all subsequent ages. He is building the case throughout that Paul is not creating something new, but is a Jew of Jews who is interpreting Jesus the only way one can - through the scriptures of the Jews. Therefore, though he only speaks directly to the point in the final chapter, the point is actually built upon throughout the whole book.
Wright does, I believe, a masterful job of taking what is obviously deep, scholarly work and putting it into terms an average Christian can understand. I think this is a much-needed gift, as deep theological works are above the ability of all but a few, yet most popular books are nothing but fluff and baptized pop-psychology.
I highly recommend this readable, and enlightened interpretation of Paul. I have a whole new outlook on Paul and look forward to reading through his letters again 'with new eyes"!