battling not giving you anything is the only real issue I had with the game, and bosses couldn't be defeated with one attack (at least not big blooper and onwards, never tried the first 2 bosses).
lack of interesting characters- high expectations because its a paper mario game.
but lookg at it as it's own game and not a paper mario game, it's flawed, sure but it has some really redeeming factors such as the soundtrack, the exceedingly awesome animations when popping a thing sticker, fighting kamek was always cool and the worlds you explored were really cool but I wish they didn't lay it out the way they did.