NOTE: there is a shiny silver "A" on the side of the lens in the picture, meaning this is their "Art" line of lenses - the same breed as the 35/1.4 that has blown away many many people.
It's also proof positive that the pic is a fake. IIRC the Art designation is for lenses with a large maximum aperture.
It should be 'contemporary' (C).
Still, I think the lens might be real. Calling this 'A' vs 'C' appeals to the people likely to buy the lens so it makes sense from a marketing perspective.
Lacking however, as with the 35mm: Weather sealing...
And (if this Sigma is real) there's where the 24-105L still wins as a do-it-all travel lens. India would have killed my camera/lens without weather sealing!
5D3, 5D2, G5X, G16 | SY14/2.8, V20/3.5, 28/2.8 IS, Ʃ35/1.4, 50/1.8, 50/1.8 STM, Ʃ50/1.4 EX, 100/2.8L IS Macro, 16-35/4L IS, 24-105/4L IS, 70-200/2.8L IS II, 1.4x II, 2.0x III, T28-300 VC PZD, 70-300L IS, Ʃ150-600 OS HSM S