To make a viewpoint based on little experience ...
As the promotional material says, the new coating reduces flare significantly compared to the mkI, but (see above) does not completely eliminate it.
I usually use this lens on a tripod & aperture relatively closed (~f/11), and I'm happy with both color and sharpness. Definitely doesn't compete with Canon L lenses I've used (135mm f/2L, 70-200mm f/2.8 IS II USM).
Haven't noticed any chromatic aberations (which I've noticed in 85mm f/1.8 and defished w/ DxO photos of the EF 15mm f/2.
, but I wasn't pixel peeping.
I've volounteered myself w/ equipment as assistance videographer for a friend's clip, and both the videographer & friend liked the lens' effect and everything taken with this lens went into the final version (which, IMHO, is what counts)
. Do note the video is at lower resolution and view size than the 5D's full resolution. When going into shade in late afternoon, the widest aperture was too slow to shoot video comfortably, so we switched to 50mm f/1.4.
My basic attitude is there's nothing to compete with this lens at the wide end, definitely not at it's price range, so I didn't check the horse's teeth.