thats a good question. i been asking myself the same thing.
most likely spoilers ahead:
it feels like pokemon snap + breath of the wild.
do the same thing over and over again until you complete a pokedex entry.
i guess what makes me want to play is the fun of running around everywhere and trying to figure out how to catch a new pokemon i discover without it running away. you dont just throw a pokeball, sometimes they block it (mr mime puts up a shield if he sees you, etc..) so i guess, what makes it appealing is the challenge to complete the pokedex. (hint: catching a pokemon once isnt enough to complete the pokedex entry, you have to catch multiple and or do different things, like feed it/see it use certain attacks, catch different forms, etc...).
Variety in places to explore, lots of quests, catching pokemon for the Dex is actually fun for once, it's kinda metal that Pokémon are trying to kill you, it's very botw-like with the fact that you can explore where you can manage to get to, but you might get wrecked by enemies. Item collecting isn't a chore and gives you something engaging to do while stalking new pokemon to catch, building your team is fun.
I think it's fine. My only concern are the graphics that are a bit too meh, considering there are is a loading everytime you hop into a different area. I think BOTW still is the king when it comes to openworld.
But graphics put aside, it really is unique, so i think it'll do fine.