I think this is a very good game for a number of reasons. I'll just list the pros and cons to save time, I guess.
Pros:
- open world (After the tutorial you can literally go fight the last gym. You'll lose, but you can try it.
- the music is really good
- the gameplay is super fun
- there are 103 new Pokémon. We haven't gotten that many since Gen 5
- the story is SO much better than sw/sh
Cons:
- the colors are vibrant but it's kinda ugly to look at
- no level scaling
- the performance is god awful sometimes (specifically Casseroya Lake, Tagtree Thicket, and the bamboo area)
- pop in is not good at all
- NPCs walk at 4 fps in the background
- You can't enter buildings in cities and the shops are just menus (but this actually proves to be more efficient as you don't need to deal with loading screens)
In my opinion, the pros outweigh the cons. While the game is not visually appealing, it certainly is entertaining, which to me, makes it worth the buy.