Finished the game today and was very thorough about it. Clocked in at a little over 45 hours, so... phew. That was an undertaking. Great game, though, and I'm glad I waited for the Proud Nordics release even though the release strategy was moronic. The extra content in the new version was excellent.
I'm going to stick with my earlier sentiment that Ys X isn't as good as VIII, but it's better than IX. I liked the seafaring more than I expected to, and it felt like a nice diversion from running around and smacking enemies. It added a sense of adventure to the game that wasn't there in the previous titles. But that said, it also made the world feel less cohesive overall, and the islands felt more generic than I would've liked, rather than the more distinctive areas in Ys VIII. I do hope the next game takes a different approach to the formula - after 3 games like this, I'm kinda good. Great games, but they do have a tendency to be overlong and the combat can get repetitive when there's so much of it. I quite liked the characters, story, and setting this time around - Karja was a super likeable companion, and I was a big fan of the viking-esque backdrop. The story was pretty standard fare, but very likeable and with a surprisingly emotional end. Just a really satisfying game all around.
The new stuff they added to the game is pretty substantial, as it turns out. I had to look up the changes since I didn't play the original, but there are a ton of QOL improvements, and the new area is easily the best in the entire game and pretty beefy. I don't think the changes warrant a full-priced repurchase (especially since this is... what? $70?), but it is pretty great.
So yeah, really liked it. If you haven't played Ys X, you really should correct that.