I have made many, many panoramas, but none in the multi-gigapixel range, so I realize that they had a very tough stitching job, but even so: This was a pretty bad job!
All the central snow fields look like the result of randomly placed images: With a motorized pano head they should have been able to locate each image pretty accurately even before they started the SIFT runs to look for matching key points (which can be hard in a blue sky or on white snow).
More problematic is the fact that they must have done the actual stitching pretty much without proper blending from one image to the next:
Within the first minute of zooming around in the image I stumbled across a perfectly straight line with totally different exposure/lighting on each side, giving an almost black/white boundary that screams "This isn't natural!".
The proper way to blend such images is to use a multi-spectral approach: Low frequency information (like average light level) is blended across the entire overlap, while higher frequencies use narrower and narrower bands. Doing it this way means that even if one image had a clear blue sky and the next was taken when the sun was hidden by a cloud, the overlap is nearly perfect.