I need to talk to someone about this. So I just beat Trails In The Sky FC. I enjoyed my time with the game, but the incredibly slow story and the simplistic battle system wore pretty thin every now and then. The saving grace was that the game actually started developing a story in the last two chapters.

Spoiler Time: So over the course of the game, Estelle falls in love with Joshua, and every time this came up in the game, it pained me so much. If they weren't siblings, then I could \have probably gotten over this. Now, I know they're not blood-related, and they have only been siblings for five years, but I feel like that's enough. I've seen my fair share of anime, and this just comes across with that this-is-totally-incestuous-but-it's-not tone. Don't make it weird. On top of that, the way their love is written and presented just feels so manufactured. So, the ending setting up the sequel as, Estelle and Joshua are in love, but Joshua left and it's up to Estelle to bring him back, is like the worst place this story could have gone for me. It also doesn't help that the sequel looks like the exact same game mechanically, which would be pretty disappointing if true.

At the very least, I'm not playing SC right away. I need some time away from this series first.

What did everyone else think of the ending? I feel like I may be in the minority here, since it seems most people that play this game speak very highly of it.

I'm not a fan of their relationship, myself. It's one of my least favored aspects of the story, but they happen to be the main characters so it gets a relatively central role. I'm usually paying more attention to everything else, as that's where my interest lies. I'm not bothered by the theoretical incest question, though. On the vast continuum of human rules and customs regarding family and relationships, their situation seems pretty benign.

Since you mentioned SC's mechanics... They're very similar: essentially it's "Episode 2". The UI is mostly the same. They do add some things and make some small iterations on the battle mechanics (Chain attacks, new orbament/orbal arts, etc.), but it's nothing crazy. Also, the game seems more difficult especially during the beginning and the end. I chose Normal difficulty and was surprised by how much tougher it felt compared to FC. If you feel burned out after FC, it might be wise to wait a bit on SC.

I'm okay with the Estelle/Joshua relationship. Is it a little weird? Absolutely. But I've just binge-watched the first few seasons of Downton Abbey and this situation seems far less cringeworthy than the strange, high-profile, semi-incestuous marriages that occurred on in 1910's England. I'll chock the discomfort up to Japanese anime norms and building a fantasy monarchic world.

Regarding the story as a whole, I really enjoyed the overarching plot. It was interesting enough to keep me invested, and made some really interesting moves towards the end. I thought Joshua's background was explained in a way reminiscent of Bioshock 1, and it makes me look forward to what will happen in SC.