I had fun. The controls are good for platforming but a bit imprecise when hitting demons. Combined with the knife's short range i found them pretty tough to kill. Giving a bit more hitpoints to duck and less to demons would perhaps make it feel more fair. Also wish the it had a bit more accurate hitboxes and feedback when getting hit. I enjoyed how the demons chase you, it adds quite some challenge.
Also, if he ever gets the time please tell your duck to rescue my mine :)