So I finished the game by catching Arceus, and I figured that I'd finally stop lurking this place, since I definitely have Very Important Thoughts about this game
I'll start with the pros, since overall I'm much more happy with the game than I am critical of it, and its good points deserve to be highlighted.
* Sinnoh was translated quite well to a different style of game entirely. Admittedly there were some moments where I was baffled by the geography of something things - I don't know why Stark Island is tiny, for instance - but generally speaking, the region felt recognizable despite having been transposed from a flat 2D grid to a 3D, more open environment. The environments are memorable, but are also cohesive enough with both itself and the Sinnoh of Gen 4 that I never questioned if this was really the Sinnoh I knew (except, again, for Stark Island - why is it so small?!).
* The return of cross-gen evos is a joy to see. Having finally prevailed in the 10-year-long War of the Eviolite, it's good to see that GF is willing to concede that retcons sometimes happen in a series like this and finally return to such a great method of breathing new life into old lines. This isn't to say things like Megas or regional forms are bad by any stretch, but rather that something like Wyrdeer stands out more than, say, a Galarian Stantler with no evolution would have. While I question the choice of giving Ursaring of all 'mons an evolution, otherwise I quite like Kleavor, Wyrdeer, Basculegion, Sneasler, and Overqwil (even if I dislike that the latter two only evolve through Hisuian forms - regular Scyther evolves into Kleavor, so what's the issue with Sneasler and Overqwil?)
* The Pokedex is a much more compelling system in this game than in the past, and I'd welcome its concepts being implemented in the main series, albeit with less in the way of repeating tasks given how there's a greater disconnect between movement and captures in mainline. Everyone loves this, and GF would be remiss not to build on it in the future given how otherwise-stagnant the Pokedex has been in the series. This game's greater emphasis on catching than battling was admittedly very jarring at first, but once you adapt to the new gameplay flow, it's quite fun to fill out your Dex and climb in the ranks.
* Grit is an excellent replacement for EVs and IVs in the context of the main-game, and I'd be glad to see a similar mechanic in the main series.
* Was Volo a predictable antagonist? Yes. Do I still love him? Absolutely yes! I had him pegged as an antagonist the moment he was revealed, but he was an enjoyable character all the way through, and having the final battle be against Cynthia's ancestor (with a fittingly sinister theme) was a joy. Cogita was also quite a nice surprise, and was definitely a highlight of the lategame - just enough mystery to be compelling, yet we get enough of a insight into her as a person that interactions with her never felt lacking. As a side-note, Adaman and Irida were also quite likable, as were Palina and Iscan, even if I don't consider them highlights in the same way as I do Volo and Cogita.
* Noble battles were a lot of fun! I wish they took some more cues from the Totems of Alola with helper 'mons, especially given that 1v2 and 1v3 battles already exist in this game's context, and the infinite supply of balms gets a little silly after a while, but they were all enjoyable in their own right. I also appreciated how the difficulty (except for Arceus) was essentially alterable at your own whims - thanks to the resume feature letting you choose between starting at the HP threshold you last met or starting over, you could opt to just stand still, throw balms and resume your progress until you won, or commit to overcoming the fight. Avalugg in particular was a nice surprise for these fights - wasn't expecting him to be Dynamaxed in all but name (and smoke)! Who said Ice types couldn't be good final bosses?
Now for negatives. While none of these things are game-ruining by any stretch, I think they're pretty glaring issues, and I'd like to see them ironed out for future Legends games (and mainline, should they choose to implement elements of Legends there).
* The graphics are bad. Everyone and their grandmother has discussed this to death, so I can't add anything new to this conversation, but I will say that crunch culture strikes me as a more likely culprit than GF being bad devs - but at the same time, seeing a powerpoint Crobat in the background makes me question why GF can't hire even a few more employees.
* Crafting is a system mindlessly imported from BOTW without considering why it works in BOTW. Smashing rocks or trees every few seconds to stock up on resources isn't engaging, it's a chore - and at a point, I was just buying crafting materials rather than gathering them, which is a much more efficient use of my time. There's also just too much stuff to craft, and not enough incentive to craft them; there's never really a reason to make any of the better lures or stun items when Oran berries and spoiled apricorns work 9 times out of 10, especially in tandem with smoke bombs. Combine that with obscenely limited bag space with a hefty price tag to increase, and I would be glad to see this gone entirely. Shops are a perfectly fine economy for games, and Pokemon should be the main draw of this game's environment anyhow.
* The regional forms were for the most part, in my opinion, pretty weak. Hopefully they get new abilities when Home compatibility hits, because otherwise they all feel very uninspired. For the most part, it was just the same Pokemon, but with a new type and more details stapled on. Arcanine gets a Rock typing with a rock coating, Electrode gets Grass and gets a wood polish, so on and so forth. They even mostly keep the same statlines! The exceptions were Hisuian Zoroark and Braviary, both of which I find to be great designs and sufficiently distinct from their original forms.
* I found that except for Wyrdeer, all of the ride pokemon felt really bad to use. Ursaluna has an awkward gait and is much too slow for my liking, Basculegion's speed was never quite right and made catching water 'mons grueling, Braviary is just a glorified glider despite being a bird, and worst of all, Sneasler is latching on and off ledges every 5 seconds and has an incredibly awkward control scheme. There was never an instance where I felt like the gameplay was genuinely *improved* by the addition of these, and it's a bad sign when I don't regard ride 'mons as useful tools, but as burdens thrust on me until I can get back on Wyrdeer or my own two feet.
* Having most characters be ancestors was kinda charming at first, but the more I dwell on it is an extremely cheap way to get people invested, and is used far too often. Like I said before, I think Volo and Cogita stand out on their own without simply being "Cynthia's ancestors", but for many side characters it was very blatant to me that the game was relying on your meta knowledge of who's ancestor this is to get you attached. Pokemon's characterization of its humans has never been a strong point for the most part, but I can't tell you anything meaningful about many of the characters besides "I guess they're ancestors of", and most of them are so paper-thin that any discussion about them just boils down to "well, they share some superficial traits with x or y character, so I guess they're the ancestor of them!" It's such a transparent way to get people attached without actually doing any writing that I'm surprised it's not a more common criticism. On the topic of characters...
* Commander Kamado is awful. Moreover, he's a realistic kind of awful; paranoia and shortsightedness are both all-too-common traits, and all of us know too well useless leaders who do nothing but sit at the top and let their employees take the fall for them - but I hate him, and I wish the game addressed him being a genuinely horrible leader more. He does nothing for the entire game but spit orders at you, and his reward to you for doing everything perfectly is to exile you and threaten to re-ignite the conflict that he allegedly solved. It's a wonder that no one in Jubilife seems to realize that he should have been removed from his post long ago.
* I hate the battle system in the context of trainer battles. Things hitting as hard as they do, and the Agile/Strong Style system, works fine for fights with Alpha and Noble 'mons since there's the inherent dichotomy of 6 v 1, but trainer battles devolve into revenge kills. With this in tandem with competent trainers being a non-existent breed in Hisui, this game's battles are its weakest link in terms of gempaly. Like the graphics, I think plenty of people have discussed this at length, so I don't see anything more I can add. As someone who loves battles, this was easily the most disappointing part of the game for me, except for...
My biggest gripe, above all others, is something ultimately very subjective, but something that bothered me throughout almost the entire experience, and it's this: when I play a game called Legends, I want to, you know, experience the Legends - not have them told to me once more. The decision to place this game in the ~1800s is something I don't like, even if I understand its real world basis in the colonization of Hokkaido. I think you could have incorporated that real-world element without making it a complete analogue in terms of historicity. Aside from Giratina (and Shaymin, actually - seeing Floaroma's origins was fantastic), I don't feel like I have any real new insight to the, well, legends of Sinnoh; sure, Dialga and Palkia got new forms, but what do they really tell me about their lore in any meaningful way? I'm not saying that we should know everything about these incomprehensible cosmic beings, as that takes the fun out of it - but conversely, I never felt like I was experiencing the legends, just its leftovers. The game puts you in this weird midpoint of Sinnoh's history where all of the notable events have already seemed to happen and everything else interesting will happen long after Kamado bites the dust (I'll be throwing the afterparty after his funeral btw, all of Hisui is invited). The game's catalyst for its mysteries is the spacetime portal above Mt. Coronet, but that doesn't strike me as interesting enough, and trying to center the game around no one knowing who Arceus is is odd when you know damn well who Arceus is.
Even though I typed much more about the flaws of this game than what I like about it, I should emphasize that I think this game was a great, albeit flawed experience, and that hopefully one day we can look back at this game as a first step into something even better - shaky in some ways, yes, but an important starting point that finds its footing as it goes, and with any luck we'll see this new formula improve over time. We're probably a few years off from it, but I have to say I'm already looking forward to Legends Kyurem - or whatever comes before that, I suppose!