Gonna agree with the consensus that it's a really solid entry that does a lot in moving the series forward, just gonna offer a few (mostly negative) opinions not expressed yet. Not really Plot but still decent Spoilers below, enter at your own risk.
The Framerate is pretty awful at different points in the game. While Totem battles are a super fun challenge, they shouldn't drop your frames into the teens in a game made in 2016. It's clear that they're pushing the system to its limits, but cmon guys, this wasn't an issue in XY and you're using the exact same engine.
The Post Game is honestly really bad. It's just the Battle Royales really, and the AI and previously mentioned Framerate for those are a joke. Even if they worked perfectly, it's still a bizarre format that's hard to take seriously, as well as pretty much the only way to earn late-game currency.
There's some weirdness with the Elite 4 where 3 of the members are NPC's who've helped you throughout the game, which is a really cool idea and it feels good defeating them and sort of surpassing your elders, but then one of them is just some random chick with birds. The fuck? She has a golf club... and throws birds at you. Could they not think of other NPCs to throw at you? Cuz I can, and I didn't even pay that much attention to the story. Just really out there and not in a good way.
At this point, I feel like we NEED a "I've played this game since I was seven I don't need a tutorial" option. The beginning of this game is an absolute chore, taking hours and hours to get through crummy dialogue. The story picks up a bit, sure, but at the start it's just the same old crap. Compare it to Leaf Green, my personal favorite in the series, where the intro is going to be, at most, 45 minutes. Here it's an entire island of invisible walls and clunky dialogue.
Speaking of invisible walls, they're **everywhere** in this game. We've had a few in previous games, but usually those were to close off the only path to an entirely new area of the map, and they had an in-universe explanation like "oh the power's out" or "you need badges to get through to the elite 4". Here it's just random dudes standing by knee high fences, or the worst offender is this asshole kid riding a doggy pokemon who's sniffing around and says "Sorry, Stoutland needs to be real thorough!" while he blocks off a fucking highway for a solid 5 hours of the game. Even if it was a problem before, that's no excuse for this level of contrived bullshit in a modern game.
Don't get me wrong, the game is full of great stuff, but damn is it annoying from time to time.