I would call it a puzzle platformer, except there is no platforming involved because you can fly. However, it is a puzzle game that involves skill similar to platforming.
The game looks cute and relaxing, but is anything but. One of the hardest games I have ever played (I haven't play dark souls though). If you like repeating one bit over and over again to get a better time to repeat another level to get a better time ad infinitum to attempt to get one of the top global averages you will probably love this game.
Only lacks one thing, and that is a custom level creator that is integrated with the Steam workshop. This isn't bad though as there is plenty of hard levels to play after the main story is beaten. If you are worried about not much content don't be.