i found the game quite addicting at the beginning and i have been playing this for a long time to earn more medal points, but to be frank, the game was poorly designed and i am under the impression that the in game challenges have not been tested throughoutly because the game interface is not very player friendly, and more importantly, some of the later levels are actually impossible.
take an example: battle 15, gold challenge.
i was not allowed to use any items to boost the stats during battle and the damage i deal is halved. this makes it impossible to beat that level because all the enemies have more than 50 health points and i can only inflict 1 HP damage at a time. the only way to pass that level is to perform 100 combos easily, which is clearly beyond anyones' ability.
being not able to completely all challenges is still not a big problem. the level upgrade system, which is not well desgined, matters a lot. the experience requirement increases exponentially with each level, and i have to spend an excessive amount of time to earn enough EXP to tackle stronger enemies. the character stat upgrade system should be more flexible. that is, players should be able to adjust the health points, attack points, etc..., so that we don't have to start over again in case i didn't upgrade the attributes smartly.
there should be hot keys. i sometimes press the wrong button in the attack menu because the screen moves. to make matter worse, occasionally i was not able to aim at the enemies with the right force when the enemies are at the bottom of the screen. we should have the option to zoom in or out.
the major portion is way too expensive and it is often more economical to buy the medium porton instead.
not every aspect about the game is covered in the tutorial. for example, it takes me a while to notice that the attack bar fills up slowly if you approach the enemy with less speed.
overall, there is nothing too interesting about the concept of the game, however, the game could be much more enjoyable if all these problems are fixed.