I have to say once again Sigma surprised me quite nicely. Despite being a bit slower aperture-wise and, by default, weaker than the new lenses from Canon/Nikon when it comes to apertures and vignetting, it didn’t have any problems to win a resolution duel with them.
High quality casing,, Excellent image quality in the frame centre no matter what focal length you employ,, Very good image quality on the edge of APS-C sensor,, Good image quality on the edge of full frame,, Lack of problems with spherical aberration,, Slight lateral chromatic aberration,,...
Distinct vignetting at longer focal lengths on full frame,, A bit too many flares and losses of contrast during the work against bright light,, Minimum focusing distance the worst in this class of equipment,, Slow autofocus.