FWIW, I thought the game did a better job than I expected it would, coming off TLOU2, of delivering some heartfelt moments. For as flat as Jin is early on, there's some good stuff going on in Act 3 that resonated with me more than I would have expected. I would even go so far to say that I felt some of this stuff a bit more than some of the moments in TLOU, if only because it feels like you're building your own story more in the open world.
That said, while I like the setup for the postgame content (and I still have some tales I want to clear out, which is kinda rare for me in an open-world game -- often I'm done when I'm done), there were some broad plot bits I didn't love:
- Mongols learning how to make poison after Jin murders them at the castle. How did this happen? You murder everyone and then during the duel with Ryuzo (where he says, IIRC, that Khotun Khan has left), a small team of Mongol CSIs probes the scene? (I think the plot point of "the Mongols learn how to make poison due to Jin's tactics" is fine, but it didn't really work for me as delivered.)
- Mongols preparing to attack the mainland, after you've massively disrupted their occupation of Tsushima, seemed especially ridiculous to me. It didn't hamper my enjoyment of the story because it was much more about the personal angle, but it did seem kinda silly. They are hardly holding onto this little island, now on to their conquest of the Japanese mainland!