Color, saturation and hue are good. Brightness and contrast are good as well. Skin tones are very natural.
Focus is good. Depth of field is soft in the foreground, as evidenced by the hand, and a bit deep in the background. The hair is rendered sharply and I think it causes distraction.
I have to agree that the hand has become an unintended subject, as it is cutting the intended subject in two, and dominates the center of the photo with size and brightness. I would recommend leaving it out of the picture.
The strings were a good idea for the challenge, and I'm wondering how a shot down the neck of the instrument, letting the strings dissapear into the distance, would have worked.