I just got it. Very impressed with the brightness and responsiveness of the autofocus. The sharpness seems very good. The weight is much more important than a lower target range (as Nikkor 18-200mm VR 1 boxing ... that does not at all in the same category), but remains in the standard of a 200 mm f / 2, 8 ... I have not had time to check whether it was actually better than the Sigma tropicalized (joints) but I'm still looking what differentiates the equivalent of Nikon ... except its lower price 40% (1150x1,65 = 1897).
