I generally agree with this, but would add a couple of comments:
Paul is mainly addressing the Judaizers who claimed Gentile converts had to basically become Jews (keep the works of the LAW, such as circumcision, Sabbath observance, food laws etc) to be come Christians. Paul pointed out the Law's main purpose was to show how we ALL fall short of God's holy standard, that Christ fulfilled the righteous requirements of the Law and died in our place, and how we (Jew or Gentile) could be justified (reckoned righteous) by faith in Christ apart from the deeds of the Law (Romans 3:28). Justification is God reckoning us righteous based on the merit of Christ which we apprehend by a living faith and not by any merit of our own.
James is concerned with those who have an intellectual faith (in correct doctrine) but who have no works of love in their life, and he teaches that such faith is dead and profitless for salvation. One must have works to 'make perfect'/complete one's 'faith' (intellectual assent to the Gospel) in order for one's faith to be living and not dead. This is really no different than Paul saying it is a 'faith working through love' which avails for anything in Christ (Gal 5:6)--in otherwords, a lively faith. Justification here is God reckoning us (judging us) righteous according to the evidence (works) of a lively faith in Christ. Merit is not in view here.
Of course both agree with Jesus who stated that branches that abide (by faith) in Him will bear fruit (John 15).
So both Paul and James speak of justification in regards to salvation but from two different angles.
--Paul is concerned with the meritorious ground for justification which is Christ's work alone and apprehended by faith apart from any merit of our own. (Thus the believer is justified in this sense as soon as he is in Christ, and for as long as he abides in Christ)
--James is concerned about the character of our faith, which is shown to be truly 'alive' (and thus actually profitable for salvation*) according to the evidence of works of love in our lives.
(*again, see Gal 5:6)
To sum up, justification in both senses belong to those who are genuinely attached to the Vine. Those who are IN CHRIST have HIS perfect righteousness imputed to them, and they are proved to be truly in HIM by the fruit in their lives.