I think that these two episodes, even taken on their own completely ignoring the first series, do a pretty good job of covering all the bases of the appeal of the childhood friend romance and how those usually play out in galge: knowing each other forever, having lots of memories, being a natural part of each other's lives, and at some point realizing that the relationship you have with each other is irreplaceable. I think Junichi's realization that not only did he love Rihoko but that he has
always loved her without even realizing it is on the one hand obvious, but also the key. It was the combination of them starting to come to face with what would happen after high school (in sense, the integration of the senpais was good) and that incident with the lowlife classmate who just wanted to "score" that served as the trigger to finally make the change. Mission successful.
The only problem with this arc is that it obviously begs the question of "what happens next". I guess on the one hand it's obvious: not much changes, because they've been together forever anyway. But we don't really get a chance to see any of the future; just the confession, the kiss (which we don't really see that well anyway), and Miya getting the hint that something's changed. It's very much redemption for people who felt she didn't have a good arc in the first series (as this completes that nicely), but it still leaves me feeling that they could really use
another sequel to show what happens next.
Anyway, I quite liked this arc, though I do wish they didn't leave the confession to the very end so we could have had a bit more "now in a relationship" time.