As a taste, I found this introduction to theological issues in Romans very satisfying.
Although Romans is an 'occasional letter,' inasmuch as [sic] it was occasioned by the circumstances of Paul and the Romans, it remains a profoundly theological document that deals with issues central to humanity's relationship with God. This is not to say that Romans is a theological essay or a systematic compendium of Paul's theology. But it is a religious document composed by a man who has reflected deeply on the significance of the saving justice that God manifested in Christ.--Frank J. Matera, Romans (Paideia; Grand Rapids: Baker, 2010), 20-21
In doing so, Paul presents us with a series of insights that are foundational for the Christian understanding of the human person (anthropology), God's redemptive work in Christ (Christology and soteriology), the new community of believers whom God has called and sanctified in Jesus Christ (ecclesiology), the new life that believers live in and through the power of God's Spirit (ethics), and the hope of this sanctified community (eschatology). In effect, Romans provides us with the outline of a redemptive story that encompasses humanity's predicament prior to Christ, its redemption in Christ, and its hope for the final salvation and glorification it will enjoy when it participates in the glory that the risen Christ already enjoys.
Amazing how many biblical scholars' middle names begin with j.
Thanks for this good contribution, Professor Matera!