+1 Indeed. Pretty interesting with the focal plane movement if one thinks a little bit about that. Plenty of images with a (compared to the full image) small and quite thin focal plane. Combining these small with different angels from the center means produces a small section of a sphere. It becomes a much-more-than-normally bent focal plane. When you do this right, like here, it's a subtle exploitable effect. But in a 180degree panorama it just looks bad.
E.g. check the droplets in the water in the image' lower right side, they appear to be much more in focus than e.g. the water to the right and below the sharp branches of the tree.