I mean, I'd take Rockwell with a grain of salt. That said, it's a good lens optically. I haven't shot tests or gone looking for distortion, but when I'm shooting subjects that are square to the camera my straight lines are straight. If you're interested PM me and I may be able to send you a few raw files later this week, then you can see for yourself. The Nikkor has seemed a bit sharper and less inclined to fringing and flare than the Tokina, though I never had a shot ruined by softness or distortion using either lens. A repairman and camera shop owner I know praised it heavily when I told him I had bought the lens. He pointed out the aspherical front element and said he believed it's an optically better lens than the 17-35 which he now uses, but not by a wide enough margin for him to bother changing back, since he does use the extra width.