The open world was a nice format change for the series and I genuinely enjoyed lurking around in the grass and catching Pokemon. I liked how you could be stealthy or run all in with battling and catching. Some Pokemon, especially when you're under-leveled and go where you shouldn't yet, were scary lol. I've seen reviews with some complaints on the world feeling empty, which I only really experienced in the first half when the pacing is slow. You see the same areas over and over again for a while.
If you're trying to complete the Pokedex consistently, most of the upsides I had start to fade from my experience. I haven't 100% completed it yet due to the tedious nature of it. It was pretty daunting to tick the same boxes for about every Pokemon. I do have to take breaks from it and do some unrelated requests which does resolve any fatigue I get from it. The Pokemon are obviously spread out in different areas like in previous games, but there were some basic ones that I got tired of seeing so often in such wide areas.
The controls felt great, I only really had issues with Sneaslers' climbing where the game would fight me with where I wanted to go, but they were very rare.
Boss fights were a lot of fun, I would compare them to a tamer Dark Souls style. Rolling and learning patterns to avoid attacks was cool. Wild/trainer battle in the game was just as fun, but it isnt a cake walk and I would dare to call it difficult at points! I could be wrong but I feel like pokemon pack more of a punch in this game. I've had my entire team wiped out because I was careless with Alpha pokemon or when battling a trainer. I loved the added challenge.
Overall I loved the game (so far, made it to credits, unsure if theres more post complete pokedex like other entries), I might replay it after the pokedex is done so that I can try to get invested in the story earlier.
ARGUABLE GAMEPLAY/STORY SPOILERS?
The story is hard to describe because I wasn't too invested/interested in it in the first half. As it progressed, it felt more and more like a chore to read the LARGE quantity of text boxes, mostly with content that felt like added little to the game, story, or characters. It wasn't all like this, I felt that the pacing wasn't consistent.
All-in-all, there were some interactions that I felt were not necessary at all or could've at least been shortened. A few characters were there just to bridge an introduction to a boss fight, some where there to assist the story through and through, they all served their purpose well, I can't really put my finger on why I couldn't really get invested into their background or them individually though.
DEFINITE SPOILERS
Once I got to Alabaster Icelands I started to care about the story a bit more, and by the time I got to the Lakes, started prepping for battle, and finally beat Dialga, I was all in. The games story dug more. It picked up it's pace super quick. When you started and were moseying around the starting fieldlands up to the coastlands, the game was so simple and I think it was on purpose to ease you into the game. It was too slow imo. The game went snails pace 0-50%, slightly better at 50-75%, full steam 75-100%.