I really like this photo, the models expression is pensive and is looking away from the camera which makes it more intriguing. I also like the cropping on this photo, because it isn't central it makes it quite unusual.
The lighting on this photo is very well done, the dark shadows really accentuate the models body shape. The fact that the background has an unusual texture which makes the photo more interesting, the background wouldn't be as good if it was just white.
To improve, although the lighting helps with the model's shape, it is quite dark and some of the detail and texture is lost - for example in his hair, jewellery and left arm. Perhaps bringing back some of that texture - just a little bit, could help increase the impact of the photo.