It would be difficult to demand anything more from a lens with such a wide angle of view and a good, fixed-focal f/2.8 aperture fastness. You get high image quality in the frame centre right from the maximum relative aperture and no weak points even in the very demanding edges of full frame.
solid and sealed barrel,, excellent image quality in frame centre,, good image quality on the edge of APS-C,, sensible image quality on the edge of full frame,, lack of problems with longitudinal chromatic aberration,, imperceptible lateral chromatic aberration,, lack of problems with distortion on...
distinct distortion on full frame which, additionally, at the shortest focal lengths shows some moustache deformations,, a tad too pronounced spherical aberration,, high vignetting on full frame.