>>41317558There's a couple things but rushed late game aside, I have two big issues. The first is how so many cities, Ballonlea and Spikemuth in particular, have absolutely nothing to them other than the gym. Very literally, in the case of the latter. That's not to say older games didn't have very small towns but they were mostly early game ones, there's actually no excuse for the 7th Gym Leader's town to be a Pokemon Center and a long corridor. All of the cities feel kind of small too, Circhester is the only layout I particularly liked.
The other is how linear the routes are, there are no side areas/side quests like the mansions in past games or fun places to explore, no large and winding caves to navigate. At most you'll get a side path or two that'll lead to a TM or item but that's all. The Wild Area is nice and big but doesn't have any real 'exploration' factor to it to make up for this, it's just a big open zone.