Oh boy....one born every minute....stopped down, it's more than sharp enough.
+1 and while in the minority, it's kind of sad to see people on here over the last few days writing off the 16-35 II, 50 1.2, and other "weak" lenses. If these people actually got out there and shot with the lenses, they'd realize that lens charts and resolution tests are just part of the picture.
When it comes to sharp enough, I shot a whole campaign for a client with the "soft" Sigma 12-24 II I used to own and yet I was still able to print (cropped) photos at 40x60" for them with no problems. The 16-35II could be better, but that doesn't mean it sucks. Photographers will always be limited by their creativity and skills, not their equipment. If you don't believe me, just wait for the inevitable posts by people claiming their Otus 55mm is soft - the same people who "only shoot handheld"