There is so much in this commentary that I can't comment on, because I am not nearly at Dr. W's level of education. He is obviously an amazing man.
I did not have much of a problem with 3.21-31. There is a discussion about "forensic justification". He does not like these terms, but his clarifications seem good to me:
"...we should not immediately read a phrase like "the righteousness of God" in early Jewish or Jewish Christian sources through the lens of forensic categories. Occasionally the phrase does have a forensic sense, but this must be determined from the context. More often it refers to the character of God, which he actively expresses in his salvific work or sometimes in judgment. It is for this reason that I have avoided the traditional language of "justification" and "justify" and have preferred instead some form of usage that includes "right" or "righteous" in it. Romans 4 will discuss the matter of being reckoned as righteous, bit dikaisoyne means more that just this to Paul. It is not just about a declaration or forensic pronouncement, and the phrase "legal fiction" hardly does justice to this profound idea. God does not simply consider the sinner righteous as a result of the finished work of Christ. Through that salvific work of Christ a person has been set right--which means not only set back into a right relationship with God, or reckoned as righteous, but also set in the right moral direction as well." (p.105)
Most of the chapter seems to me to make helpful analysis and explanations. Several misunderstandings of different writers and periods are addressed.
At the very end of the chapter he does set up the idea of the new set of laws for the new covenant, which seems to me is a misunderstanding of such phrases as the law of Christ and the law of faith.
"Indeed, his promises to Israel are to be gathered up and fulfilled in Jesus in the context of the new covenant, not the continuation of the old one. So both Israel and Gentiles find themselves on a new footing with God as a result of the Christ-event. God is not keeping two contracts and two sets of laws with humankind at the same time."
Below, there is a video of Lee Strobel with Ben Witherington.