Sion is a perfect example of visual rework done wrong
http://4.bp.blogspot.com/-SkXWZrvy_zo/VCRpuOnbjuI/AAAAAAAAZi4/WPcZCYZPI5o/s1600/oldvnew.jpg
The gameplay redesign is...debatable, but there is absolutely no denying that in the visual overhaul Sion ceased to be what he was and became something else.
Old Sion was an affably villainous zombie and his appearance and mannerisms reflected on this perfectly. The new "Sion" is a confused Warcraft orc wannabe that looks nothing like a zombie and lost all his charm in favor of bland edginess.
I've always wanted to point out what a mess this visual redesign was. Why couldn't they tweak his old appearance to fit in with modern standards without changing it?