Hey, there.
Interesting piece. it has enchanting melodies all the way from start to finish, that weaves into each other almost seamlessly. The 3-against-2 rhythm, I feel, is especially instrumental to achieving the 'Nocturne' feel of the piece; it makes the piece feel very relaxing, dream-like and almost meandering. Reading the previous comments, while I agree it's rhapsodic, I will say that it feels more nocturne than rhapsody, but that's my humble opinion.
Overall, beautiful piece!