Pretty fun, but too easy for sustained play.
Perhaps you could make some harder modes. In my opinion where it fails is that the game becomes very very easy if you simply choose to spend time killing enemies, you can always kill enemies faster than they spawn if you focus on it, so it is easy to grab 2-3 lanterns, kill all the enemies that spawn as they are jumping out of their two spawn locations, and then you have no danger whatsoever as you collect 2-3 more lanterns.
What would be great would be to greatly reduce the "reload" speed of the sword slash, such that just killing all enemies is a really slow porcess and the game is more about jumping around these enemies and living with a screen full of enemies, than killing them as they spawn. In this way the game would get harder and more intense as you collect more lanterns and the enemies pile up.
That is more spawn locations.
Personally I found it too difficult, and I really enjoyed it. The difficulty spiked too hard, for me subjectively, once you hit the second level. I hope there's some levels after that. Cause the first level gets easy if you've played it once.
I keep going back to play through this again, so I guess ignore my complaint about sustained play.