The perspective and DOF is really working for me, as well as the composition. The guitar strings really draws the eye into the picture. However, I want to say the lighting on the hand is just a bit too harsh, the focus on the nails a little soft. The worn fingernails are a very nice detail, and I would have liked to see them better in focus. Also, I'm not a great fan of the color tint you chose (personally would have preferred less purple and more sepia) but that's your call.
An interesting choice for the duotone.. stands out.. nice tight crop... maybe a little more crispness in the pickin' fingers would make this really pop....... nice job