Well, all things considered, my answer is not at all.
First of all, there is a big difference between graphics and gameplay.
About the graphics, yes I can agree that it's not one of the best ones and it's probably not good compared to a lot of other games. But, it's still a Pokémon game. Considering this, comparing PLA to the other Switch games, excluding Scarlet/Violet because they are newer, it looks better in my opinion. Pokémon games are not particularly great for the graphics, so I would say this wouldn't be only about PLA, but about the Switch games in general.
About the gameplay, I feel like it was one of the best in the entire franchise. It's different, fresh and new. This doesn't mean it's perfect, but it's indeed a sweet alternative to the other main line games. It's not for everyone, this is sure. It is about completing, exploring, there are "boss fights". It's a new vision of the usual Pokemon game experience and I like that. It can be boring for some people, I guess. So, as I said before, it's probably not for everyone, but I would never say the gameplay is terrible.