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Here is the official word from Microsoft TechNet, The C:\Users folder is shared when any sub folders from C:\Users\<username>\ is shared. The article is stale and mostly unhelpful, but worth knowing to complete the story.
The second thing that was added was a preview to your shared links. If you have images, you see a nice gallery in your links and Office documents now have a preview. The downside here is that simple file hosting doesn't work by pasting in the link. To solve this, you just need to change the actual shared link with the link to the file itself.