As a professional wedding shooter, I use this lens quite often paired with a D700 where its lack of corner sharpness doesn't really matter. I would not use this lens for work where corner to corner sharpness is critical. It's fine on a crop body though. The new 70-200mm f2.8 VR II should be much better, and I will give it a test once we get ours.
Centre sharpness is brilliant, corners not so much. The Canon 70-200mm f2.8 IS is sharper in the corners, but the Sony 70-200mm f2.8G is the one to beat, in my experience.