dpreview has posted first series sample images of Sigma 24-35mm f/2 DG HSM Art lens and Canon EOS 5Ds R. See sample images of 5Ds R w/ Sigma 24-35mm f/2 Lens.
Petapixel has posted full review of Sigma 24-35mm f/2 DG HSM Art Lens, See the full review here.
The Sigma 24-35 DG HSM Art lens will excel for urban cityscape, some landscape, environmental portraiture, documentary photography, and even some street shooting. Video shooters, as well, will love this lens and the versatility that it brings, in addition to the internal zooming functionality. I refer to this lens as a prime that can zoom, and that is what it feels like to shoot. The fact that you can change the focal length of, what is essentially, a prime lens is novel and just plain useful.