I have the Tokina 11-16 in Nikon flavor comming in 5 days (stupid weekend in the way). I looked all over and the Tokina scored better than Nikon and Sigma ultrawides (more than just KR's praise). I have an older Tokina 300 2.8 and its built very well. So I believe the 11-16 will be up to par. Alot of the reviewers mention the shorter zoom range probably helps the Tokina to better control aberations and such. I was leaning towards the Sigma (price lower), but its a bit slower, and noticed they have a new model comming out that I think will be a constant aperature of 3.5. So they are picking up the speed a little bit as well. I think Nikon is a little behind in the super wide lens group. Canon's ultra wide has had a good following and would probably be the better lens for that Camera flavor. For me the Tokina won out. Will see in 5 days.