:)I opened all these files in ACR and went thru my usual editing workflow. Am very impressed with the images....Sharpness good, very nice bokeh. Lighting was pretty flat so I bumped up contrast. I have noticed some CA in other images on line but only in extreme cases,eg, tree twigs against white sky.
BTW, I have never used a full frame and I must say, these clean images from the 5D mark III make me want to get one. (I won't...due to weight,$ and crop factor)
I note that all these images were at max aperture, max focal length and were imho quite usable. Not sure if camera was tripod mounted or handheld, shutter speeds were pretty low.
My guess re: the it's too good to be true...thinking ...about such a low price, is that Tamron has projected huge sales for this....and they are willing to take a lower margin due to high sales. They will poach a lot of sales from canon, nikon and sony, not to mention Sigma. Users who could not consider a lens of this length before will consider this, eventually, other mfgrs will counter
If the web poster is lurking here, thanks a lot for doing this. Looking forward to seeing your comparisons with the 400 5.6 L