Your main subject is not in sharp focus, and the shadows are underexposed. The sky is also blown out, so you should probably just crop it out. The white balance seems a bit too yellow. You would also have had to include a model release from the man in the photo.
Exposure: You need to lighten-up the shadows and bring down the whites/highlights.
Contrast: I would add more local contrast (Texture/Clarity)
Composition: When taking the picture, it would have been better to frame the picture differently, to bring in more sky and get the photographer more on the golden ratio (you could even add more sky, getting the photographer a tick lower):
As you now can't change the framing you took, I would crop like this:
This will also cut out the too small sky stripe. However, the sky is important to orient the viewer, so think about composition, when you take a picture next time.
Looking at the picture at 100%, I have the impression that there is some digital shake compensation, noise reduction and sharpening. It would have been better to photograph more open to get some DOF. The picture should still be OK at around f8, as long as the photographer is focused. This would also have “hidden” some weakness of the lens in the corners.
The biggest problem, however, is a strange artefact around the photographer's arm (here seen at 300%):
Focus, exposure and composition.