When the Sigma 14-24mm f2. 8 Art DG came in for review, I saw the review going something like this "It's great. Get it. " Now that's not me being biased, but Sigma's Art lineup of lenses have consistently been stellar and there isn't a whole lot of argument about that.
With the Sigma 14-24mm f2. 8 Art DG you're getting the same great Sigma optics that you always get in addition to weather resistance. The fact that they took the route of tackling a 14-24mm f2. 8 optic instead of a 16-35mm also means that you've got even more range of coverage when you use their lenses. Of course, not every photographer will really need something like this as this range is typically used by architecture, environmental, landscape, and photojournalistic photographers. Not many folks need to go beyond 24mm and many even think it to be too wide. . thephoblographer.com