Oh man, where to start. I'm a fan of piano arrangements that are well put together. This song is no exception. The feeling is on a whole new level. As stated in the comments, the composer and player of the piano, Jormungand, has a very unique playing style.
This song also has an added bonus for me, as I can visualize things through listening to this song. Picture this: It's fall and you're standing in front of a huge stone mansion. Inside you can hear the sounds of a piano, simple notes to start, but then more complex as the notes seem to rebound off of each other. You step through a huge wooden door hinged with black iron and begin to follow the sounds of the piano growing ever louder. Running through the halls, feet beating down on the cherry maple floor, the piano begins to reach a peak that almost makes you want to cry. You need to find this piano, you think you've found the room, but when you burst through the iron-wrought doors, you find nothing, and the playing slows down to an almost dismal level. Now it sounds as if it's accross the mansion. Heart beating faster, you blast through the doors oncest again, while the notes from the piano pick up faster and louder. Dynamic as it is, you're almost mad with delight as you burst through opening to find a piano... but no one playing. Your heart sinks, and you begin to leave. As you pass through the huge door entrance, you smile a small smile as the piano picks up again. So the chase is on...
Perhaps that was too elaborate, but I couldn't stop myself. Anyway, that's what I feel about this piece.