It has a bright and cartoony aesthetic, which isn’t inherently bad. Objects are easily readable, and the style is very flexible for adding all sorts of characters from various settings. The style also ages better than attempting photo realism.
Otherwise, yeah sure it’s a shooter which happened to catch on for the younger audience especially, and the increase of social areas and events gave it more varied content.
I played it for about 10 minutes, it’s not really for me. I don’t think about it much, but I understand why someone might like it. Just because it isn’t for me doesn’t mean it’s bad. People that getting really riled up about it existing or being popular give the same aura as 12 year olds vocally making fun of things 10 year olds are into to prove how mature and sophisticated they are in comparison.