The game is good, but there are plenty of major flaws to start with. First, it's about this controversy of the game planning to not bring back the national dex, AT ALL. The developers see this dex as old school and believes that it ruins the mood. But by getting rid of it, they're giving the mission to catch all of them a short lifespan that will be forgotten for the rest of the entire franchise. I don't care if it's bad, it's good in many ways possible. The announcement of removing the national dex from the game became responsible for the social outrage from millions of fans who loved buying the games.
Next, I want to talk about something that really irritates me. And that would be this feature that locks the gender, stats and traits of a Pokemon you saved next to. I'm one of those people who is very picky with what nature or characteristic I want. I never go for naughty and somewhat stubborn for some reason. It's been stuck to me ever since I first played Diamond and Pearl. I once caught a Magikarp in Sword, but it had one of those so I had to leave the game and go back. And then when I caught it, it has the same traits, level and gender. I only catch males, females if they're 100% or if it's a requirement for evolution. I have my own habits. But the real thing is that not only does this anti-reset mechanic affect these, it also ruins the chances of hunters finding shinies. Gamefreak sees shiny hunting as a form of cheating, so they made a mechanic to prevent that. This angers a lot of players.
Lastly, I want to talk about what one of my friends mentioned about the rival. Hop has the same personality as Hau from Sun & Moon. Not only that, but Gamefreak re-used some Hau animations and gave them to Hop. Why can't Gamefreak make a different set of animations for the rival? How would he make a good rival is they reused some animations. Oh, and don't get me started on the Team. They're not really that intimidating.
Overall, I wouldn't recommend getting this game. It's good, but very different in the eyes veterans. Pokemon will never be the same again after this generation.