It is very challenging, at least for me it was. I am sure that those that like difficult games would love it.
It was difficult, but felt very polished, and the pixel art gorgeous.
I died sometimes just by touching a wall that did not have any obvious danger that i could see. I made a screenshot when i was trying to slide down from the left wall of the stalactite:
The only thing i think this game lacks is, maybe, a little more story. At first i thought that i was just keeping the spirit(?) company, or maybe protecting it from something during the journey, but it turns out it was me who was returning home(?).
But maybe it is just me who did not understand :-P