I think visually speaking, while the deblocked version is smoother overall, the blockiness added extra perception of noise/texture. The extra noise almost always increase the perception of sharpness and level of details, and you can see from the braids coming out of the hat that it does look sharper with the blocking version, although the wall is smoother. Would be great to include more sample images in the page.
x264 video codec developer Dark Shikari blogged about [1][2] this "fake sharpness" phenomenon. Early H.264 encoders produced excessively smooth, deblocked video, which made them look worse compared to MPEG-4 ASP (like Xvid), despite former being a newer, objectively better format. Wavelet-transform compressors like JPEG2000 had a similar problem vs. blocky JPEGs.
People's tastes are subjective, though, so it's good to have options.
