The debate surrounding justification essentially boils down to one thing: the starting point of the discussion. Is it anthropological, or theological? To put another way, what is the purpose of the doctrine of justification – is it to answer the question of ‘what must I do to be saved?’, or is it ultimately about (to borrow from Wright’s new book) the faithfulness of God? If the former is the answer, as it was for Luther and pretty much all of Protestant dogmatics for the next 500 years, then you end up with, more or less, the idea of imputed righteousness (on a historical note, the idea of imputed righteousness stems from medieval notions of merit-theology, which is why the Eastern church has never really had this debate). If the latter, then one ends up with what is broadly recognized as the ‘new perspective on Paul’, though this is a pretty misleading and possibly even obsolete term.
It seems to me that Wright is substantially correct in his take on the doctrine – yes, he is mistaken or weak in some areas (I find his christology to be a weak point) and places a lot of weight on the Second-Temple return from exile theme (which may or may not be correct, that’s a matter of debate) but broadly I see his interpretation to be correct in terms of Justification being about God’s covenant faithfulness, starting with Abraham in Genesis and reaching its climax in Christ (along with all the various points about law-keeping, ethnic boundaries, lawcourt, etc). I’m fairly firm in my belief that justification is not about answering the existential question of ‘what must I do to be saved’ but 100% about God’s faithfulness – to phrase it in a Wright-ian way, it’s not about how I get right with God but how I get to be in the right with God.