It's really good! I enjoyed the challenge progression of the levels, as well as collecting the bobbles. They were just hidden enough, and figuring out how to reach the tougher ones is a satisfying puzzle. Zoya's little advice about being able to warp to them from the collection screen was maybe the hardest I've been trolled before in a game...
I enjoyed practicing to get through each level without dying, and eventually did a speedrun of the game.