Most of the low star reviews on this game are from people who don't like the art/animation style or didn't like the difficulty and still decided to buy it. This game is made to be difficult and the controls are pretty tight. I wasn't great at this game when I started playing but I doesn't take that long to learn how to play. I think this game was well made, but you should be ready to rage a little if you want to get better. 10/10 game, the difficult is perfect because without it the game would take a couple hours to beat.
Good points from reviews:
The flying levels are MUCH harder than normal levels because there is a lot more space to move around, which the developers filled with small objects to dodge.
The music is great, but hearing it over and over CAN get annoying.
Overall I would recommend this game to annoying who enjoys the art and will take some time to get good at it.