Colors are good. Fog is good. Horizon is at a good spot. It is a good picture.
It would be considerably better with a bigger zoom and lower so that the man was 3 x as big int he frame and standing up higher against the horizon. Since the man is the interesting part and the sky water is repetitive.
A bit of vignetting on left that I would crop out.
I agree with Scott but for me, the size of the fisherman is fine.
Don't know how a D40 reacts to noise at ISO400, but I think opening up the RHS or a crop would help. I've tried something similar, posted probably a week ago in FixMeUp thread I believe, and enountered lots of noise when I tried to recover shadow detail.
BTW, colors are fantastic on this calibrated monitor (Spyder2 Express - not big $ but gets the job done for me)
Save your money and don't touch anything ... you'll only mess up something with calibration. I've somewhat gone away from visual processing, one's eyes can be tired, or one looks at the monitor at a slight angle and such.
I rely on my instruments to pull in the slider bars for colour ~ I can honestly say you'll only break something if you go "fiddling".
Beautiful image. Beautiful sky, color, saturation. My eye moves back and forth from the silhouetted fisherman to the trees on the right. Seems like a bit of competition within the frame. Or, it implies a sense of movement for the fisherman to cross the frame. But then I think, how can he head there? It seems further out in the water, a bit far away. Others may have a different narrative evoked. Interesting.
Scott