I'm not a one hell of a musician but I can tell that the harmony of notes surely is "harmonious"; each note of each instrument compliments each other. I just noticed that the viola (I'm not sure if it's the viola or violin) sounds discontinuous, like the strings starts to have a louder volume with certain oscillation when prolonged then,when changing to a new note, the volume and the oscillation cuts off abruptly. Speaking of abrupt, the ending was too sudden; it would be better if the end part fades...
Hence:
5 stars - 1/2 star (discontinuous strings) - 1/2 star (sudden ending) = 4 stars