Alright so I'll give my own elaborate opinion on sticker star.
Now as I said earlier, the game is mediocre, its biggest flaw for me isn't the lack of partners, its not the lack of a story to latch onto. No, for me its the removal of any kind of level up system, its ridiculous cryptic trial and error puzzles, the utterly stupid weakness mechanic for bosses and no long term benefit for battles.
However I feel it does have its strong points. First off the game is BEAUTIFUL. All the levels are very detailed with excellent use of lighting, colours, and they make great use of the paper style. The battles themselves are very fast paced and the attacks the most satisfying in any of the games, with hammer attacks that cause shockwaves, incinerating foes with fire balls or fire hammers or jump attacks have a nice oomph to them on impact.
It has a great sense of exploration, with lots of hidden paths and areas full of secrets and goodies to find and there is a certain level of non-linearity to the game. It also a few charms of its own, like ninji's that fold themselves into origami shuriken.
Also I love peeling things from the environment.