Bauckham argues that James -- who indeed probably wrote this letter -- was a messianic wisdom teacher who made the eschatological wisdom of Jesus his own and applied it to the resources of Jewish wisdom tradition. He refutes the artificial distinction between sappientalism and apocalypticism, showing how the two went hand-in-hand (albeit in varying degrees) throughout the 2nd-Temple period. Then, comparing the letter to the synoptic gospels, he notes features of comparison between James and Jesus: (a) the focus on the Torah's concern for ethics and the heart as the source of words and actions (Jas. 1:22-25; 3:6-8; 4:11-12); (b) a standard of community living in which solidarity with the poor replaces hierarchy and status (1:9-10; 2:1-7); (c) God's apocalyptic judgment as the overriding motivation for righteous living, with punishment especially threatening the wealthy (5:1-5) -- but no less a reality for everyone else (2:13; 3:1, 4:12, 5:8-9), as is the prospect of reward (1:12, 3:18); (d) the concern for "Israel as a light to the nations", whereby Jesus brought the Kingdom to Israel, and now James addresses Jewish communities in the diaspora (1:1) as the nucleus of the ongoing messianic movement which must serve as a beacon to the Gentiles.
The author shows that James' doctrine of works doesn't exactly correct Paul's doctrine of faith. Paul was hostile to specific kinds of works -- circumcision, food laws, holy days, or any requirements which were a stumbling block to Gentiles; James was enthusiastic for good deeds in general. His discourse in 2:14-26 is general paraenesis, a reminder that good deeds must naturally accompany one's faith, something with which Paul naturally agreed. Paul and James simply mean different things by the term "works". Likewise, they offer different, but not necessarily contradictory, exegetical interpretations of Abraham (Gal. 3:6-9/Rom. 4:1-17; Jas. 2:21-24).
I agree with this particular point, but not with the implication that Paul usually agreed with James or got along with him. In his own review Mark Goodacre notes that "Bauckham comes to us as a kind of modern-day Luke, for whom all in the early church is harmony, where disagreements are only over degrees of emphasis". Quite right, and that paints an equally misleading picture. Paul and James were serious rivals. Paul thought the law was finished, and that good deeds could follow only by another route -- the spirit; James thought the law remained in force. Paul believed in indiscriminate table-fellowship between Jew and Gentile; James did not. Etc.
Quibbles aside, this is the best commentary on James and should be mandatory reading for specialists of James and Paul alike. Bauckham no doubt has Martin Luther shrieking in his grave. Luther's contempt for James as an "epistle of straw" is well-known and still shared by many today. But instead of taking the letter as an inferior corrective to Pauline doctrine, we are compelled to come to terms with it on its own right -- as an encyclical of subversive wisdom written for Jewish communities in the diaspora.