When I was a child there was a song, Henry the eighth, which had a line "second verse, same as the first." In a sense Deuteronomy is that, a second verse. The word deuteronomy literally means "second + law" and it is structured as a long sermon by Moses reviewing the exodus event. Those who study (and cross study it with Exodus or Leviticus) the writings see an extended narrative which continues through Joshua, Judges, Samuels and Kings. In simplistic terms it is all about God's grace, God's offer of covenant, God's provision of the covenant expectations and the option of life or death, blessing or curse. It is a reflection on the saving relationship of God and His chosen ones.
Like most people, I was raised to view the "OLD Testament" with a certain level of disdain. It was old and outdated, the "god" of the Old Testament was a "god of judgment" and cruelty and as a New Testament person I had limited interest in and limited knowledge of the greatest portion of the Bible. Of course, we did cherry pick any number of cool stories (Adam and Eve, Samson, David and Goliath) usually sanitized and edited so our young ears were kept pure. The paradox, the OT was part of the Bible and the Bible is God's Word, did sort of gnaw at me at some level, but I was not consumed with the things of God and probably spend most of my time worried about the daily concerns of my existence.
As I have come to see the Ancient Covenant as foundational and Jesus as the fully-filling-up of that covenant promise of God, I have also come to a deeper reverence for God's word in both testaments/covenants. I studied the Jewish texts with the same enthusiasm as I did the Jesus texts. I learned that grace is also in the older and judgment is also in the newer, so there is not a clear differentiation. God is God, unchanging and also bigger than our theologies imagine,and He is God in both. [In seminary I found out the differentiation between the OT god and the NT God is actually a heresy: a damnable lie. In light of that I have attempted to seek truth and embrace the fullness of God's self revelation.] Lastly, and this was recent, the Easter before last, one day it dawned on me that the Ancient Covenant text (Torah, Prophets, Psalms and Wisdom) is what Jesus called the Bible and it was what He opened up to explain who He is. In other words, Jesus only needed the Ancient Covenant text (OT) to explain everything!
Deuteronomy is gracious. God chooses Israel because He wants to. He makes promises to the people and keeps His end of the bargain. The offer of abundance (land and blessings) require obedience, but how could it be otherwise? Deuternomy is a reminder that there is a time and a place. Obedience is a gift not a curse. Much of God's law is intended to shape human behaviors in imitation of God. In other words, we are to be loving, honest, fair and trustworthy. Such things are not just outward behaviors, they are also inward attitudes. We become by what we do, and we do from what we are. There is a degree of self-creation in all this. And we have a role, to be light to the world. That is Israel's task: to witness that the Lord (YHWH) is God. Their actions are as much a proclamation as their words.
So Deuteronomy is one of my favorite books of the Bible. It is loaded with wonderful wisdom and inspiring, life giving demands. It has a beauty which shines into my heart and soul. It also lays out an explanation for all of the history of God's people, right up to the bitter end of the Fall of Judah. It offers insight into our predicament today and gives light in this present darkness. And Jesus fully-fills-up the revelation given in Deuternomy.