The graphics were charming. They were only as complex as they needed to be; I have always liked that. I was rather fond of the little stars that show up when you make your hero bonk his head on something and the snow falling in the background sky. Those were nice touches. You captured the style and essence the metroidvania games and kept it simple and clean. Not an easy task.
The music was stellar, both the intro music and the main song, both of which I could see making appearances in Castlevania: Symphony of the Night. Kudos!
The game-play itself was good, but the underground section was brutal. The difficulty ramped up unexpectedly and the jumping sequences underground quickly went from interesting, to challenging, to aggravating, to near rage inducing. I would not have minded as much if I were playing on hard or death difficulty; those are supposed to be hard, but I was playing on normal.
I appreciate the simple straightforward control scheme, but It might have been worthwhile to add in a note or something that the wall jump lets you slide down walls too.
In summation: The portion I got through was excellent. I am guessing most of the rest is likewise as good, but the underground section was too unforgiving, and proved insurmountable. Notwithstanding the previous sentence, I felt this was a very well done game, doubly so given the limitations of Ludum Dare. I would love to see more of your work in the future. Kudos!