Sounds like difficulty is good, new core gameplay loop of catching and battling is good, worlds are nice and big and there are lots of side quests to do.
The downsides seem to be mediocre half-assed effort on the graphics (graphics look alright to me in pics and videos, mostly i just notice lazy effort like low res textures and the water looks pretty bad, but the IGN review video did show horrible framerate on pokemon animations once they pop into view but are still far away - hopefully terrible stuff like that gets patched), a fairly empty world (similar to critiques of BotW), and no puzzles or dungeons or anything like that which would make exploring and finding new areas exciting.
My only concern is the gameplay loop could get old after a while if exploring the big world isn't very interesting, though the side quests (which I guess come in the second half of the game) are supposed to be good, but a big part of a large world design like this is that exploring the world should be interesting. Seems so close to the ideal Pokemon game except a lack of design/development effort leaves it as a good but flawed game.
Will probably watch someone play it on Twitch before deciding to buy it, or maybe wait to see if they make some improvement through patches.