From a free to play perspective the ad walls provide a great incentive to upgrade which isn’t terrible, I understand developers need to make an income. As a whale the game if unfun the main reward for JPJ is slowly increasing your score by becoming slowly better at the game, with a level system this incentive is gone and there is little incentive to continue playing outside of upgrades which can be bought, so simply a whale could purchase finishing the game without ever having to play it.
It’s hard to know who the target audience for this game really is.