Good lighting and composition. But there seems to be a bit too much red. Perhaps it is from playing the instrument (cello?) but it looks as if it has been in the sun too much or like it came from the cold and is now warming up. Same can be seen to some extent on the nose. A slight adjustment of the mix of the red channnel in the channel mixer might easily solve that.
In my opinion, the dreadlocks throw off the theme of the rest of the shot, but I won't hold that against you. Well framed, I like how the neck bisects the image. But I wish the top of the model's head were in the frame.
Rich and evocative, beautifully composed. Separation of hair from BG on left is fantastic. Perhaps use healing brush to mute the nose higlights slightly? Very strong image.
This is one time that I think the harshness of the lighting adds to the photo. This shot is filled with emotion and I love the rich tones as well. I think it might have been slightly improved with a little looser crop keeping the elbow in the frame and leaving a bit more empty space to the back of the subject. I think that might have emphasized the look of complete concentration.
The background to the right is a bit distracting, but otherwise I can't really see much wrong with it. Nice, but would probably have been much, much nicer in B/W