This game is so cozy! I loved importing my Pokémon and seeing them interact with each other and do silly things. However, I can understand why most people don't like this game, since it's really pointless and it functions as a subpar storage service, but I still have fond memories of it nevertheless.
The only real value this game has is that it used to be one of the only legitimate ways to get Mew at the time. Otherwise, there's not much to do. I wish there were more ways to interact with your Pokémon, like in Pokémon Channel, but there really isn't. As IGN described in its review, the game just feels like a "screensaver" almost.