Upload & Sell: Off
I recently got the 18/2.8D. I did an A-B comparison with my 20/2.8D and I could not decide which was better, so call them even (I'm selling the 20 now). The 18 is a bit wider and more solidly built. The hood offers better coverage too.
The sharpness and CA may be a little worse than the zooms like the 16-35, 17-35, and 14-24, but it isn't like the 18 sucks. The pictures look good and sharp to me at reasonable viewing sizes. The distortion on the 18 is not bad at all. I think some of the criticism that the 18 and 20 get is based on test sites and pixel peepers. And I think the "Internet amplification" factor comes into play as well. Nikon only ever made about 7000 of the 18mm lenses, so a lot of people commenting on it have never held one in their hand. But, with day to day use of the 18mm lens, I find it quite pleasing and I will keep it permanently. BTW, I am shooting it with a D800.