I have been using this lens since July
and absolutly love it. I learned about it on kenrockwells site and ordered it before it was available. Trusting Ken's review I sold my nikon 12-24 for $750 before the value started to drop and even before I had the tokina in my hand. Thus I was able to pocket almost $200 and have a superior lens. The only thing I miss is the longer zoom range of the nikon. The 2.8 aperture and the fact that I maunly use it pinned to 11mm make this not so hard to miss. That said if you ever walked around with a 35mm lens on a film camera you know how versatile that focal length is. This is about 20-23mm on a DX nikon and I wish nikon made a super fast 20mm lens with no distortion. When traveling light I carry this tokina and my 35mm F2.
Everything turned out to be true with this lens. perhaps the most notable thing is that it actually focuses correctly on infinity. The Nikon always left distant objects out of focus because it focused past infinity.
Next best thing is the minimal distortion. Look at this image at left. I think that there is no distortion worth correcting. The image is sharp with only minor softness and falloff in the corners. Best of all this is at 2.8 1000 iso and 1/8. I shot three images in C mode and picked this one as it had no blur. Pushing the shutter button shakes the camera so let it fly and pick the best image.
Anyone that doubhts the value of fast lenses should do this test. Shoot say a 18-70 at 50mm at 5.6 in dim light that calls for 1/30 of second. Now take the same shot with a 50mm 1.8 lens using f5.6 as well. The differance is staggering. Try the same in bright light and it will not be as noticable. Want to see more from this lens try this link.