Looking for something different to listen to? How much more different can you get than "video game music, in the style of bluegrass"? This is a fantastic concept, and it's executed extremely well.
My favorite track has to be Dance of Pales from Castlevania: SotN. It's a great waltz that carries the listener through a soundscape that is simultaneously eerie and wistful, and it's just fun to listen to!
Favorite track: Dance of Pales (from "Castlevania: Symphony of the Night").