The price of the recess objective image quality is superb !, the photos are very fine and full of detail, stabilization is very effective.
Noted a slight vignetting is present at full aperture (nothing dextraordinaire).
Another thing I like is the attachment of the lens hood and the pinch lens cover system that is much more convenient than my 24-105 especially whether to replace the cover when the visor sun is still equipped (those with 24-105 understand).
Some blame his weight, for me it is not a defect, I'm not Superman and yet I ride me for hours with the device in hand ...
Only small thing to complain about is the space between the foot of the collar and the goal that is not important enough, so that you can not insert your fingers between the foot and the goal (though I ' have thin fingers), and suddenly the focus ring is a tendency to touch, so be careful.
So I put 4/5 for the collar makes this goal is not "perfect."