In this chapter, David gives the gathered materials for building the temple to Solomon and Solomon inherits the kingdom from David.
This chapter is the conclusion of David's life in the Chronicles narrative, in more than one way.
Figuratively, this chapter is the culmination of David's vast labors on behalf of the temple. As I've discussed at length, the past several chapters of Chronicles form a chiasm. It begins by building up a litany of David's preparations, both material and structural. David gathers gold, silver, fine wood and stone. Then he organizes the priests and Levites into the temple service. In the second half of the chiasm, David gives these things to Solomon. In the last chapter, David gave the priest and Levite organization to Solomon, as well as plans for the temple building itself. In this chapter, the chiasm concludes when David gives the material goods to Solomon. This chiasm is representative of David's ambition for the temple, so when he gives the last of the material goods to Solomon, it effectively ends his worldly obligations.
Literally, David dies in this chapter and Solomon inherits the kingdom from him. Having completed his earthly mission, David has no other role to play in the Chronicles narrative so his story ends here.
Just as this chapter is the end of David's role in Chronicles, it is the beginning of Solomon's place as he is made king "a second time" (v. 22), reigns in David's place, and has formally taken on the obligation to build the temple as commanded by his father.
The narrative in this chapter is overwhelmingly positive. Besides the devotion of David and Solomon towards this great building project, we also see the commanders and leaders of Israel donating what they can afford towards the temple project. This is an obvious parallel to Exodus 35:20-29 when the people of Israel gave voluntary donations towards the construction of the tabernacle of Moses. This continues a general pattern in Chronicles of drawing parallels between the stories about the tabernacle of Moses and the temple of David and Solomon. In other places, it's by implicitly comparing David and Moses, but here it is by comparing the narrative of how these two structures were built.
As in Exodus, the people and their leaders are demonstrating wholehearted devotion to God and the king. In another parallel between Exodus and Chronicles, we know that this devotion will be short-lived as the generations to follow swiftly devolve into idolatry and sin. For the moment, though, things seem very positive. The turmoil of Solomon's ascension to power and Adonijah's treachery (1 Kings 1) is omitted entirely from Chronicles. Rather than seeing a nation divided and a bunch of executions (1 Kings 2), we see the entire nation united in following Solomon (v. 23-24). In the vision of the Chronicler, this is the pinnacle of Israel's history.
I think that's pretty much it for the big thematic elements. There are a few minor notes I would also like to include.
Once again we see people eating and drinking (v. 21-22) to secure a covenant. In this case, it is a covenant between the people, God and the king, with the people swearing their obedience to the new king Solomon and to the LORD (v. 20). Not only did the people acknowledge Solomon as king, but the LORD himself granted his favor and blessing to Solomon (v. 25).
In verses 18-19 we see David ask for the LORD to preserve the people's faith and dedication to the LORD, to "direct their heart to you", and to "give Solomon a perfect heart to keep your commandments". I think this is interesting because theologically it implies that devotion to God itself comes from God, or at least we can ask God to increase our devotion to him. I'm not entirely sure how that works because you need to have some kind of devotion to God to even pray something like that, but for anyone who has devotion to God or at least wants devotion to God, it appears that it is something you can quite simply ask for.
Lastly, verse 29 lists the sources used by the Chronicler when writing his account. Out of these three books, we have already read the book of Samuel and the books of Gad and Nathan no longer exist (no extant copies).
With that, we conclude the book of 1 Chronicles and now we can move on to the second half of the Chronicles narrative, beginning with the life and deeds of Solomon!