I was going to point you to the release notes http://releasenotes.xara.hosting/designer-pro-x16/ but as you can see if you click on this link, the page is not found.

So maybe nothing to see here folks. Move along.

As I remember there are a lot of new and improved smart shapes, and tables. Added support for Open Type Style sets and ligatures and other text tool improvements. Text inside a shape which is not high on my list of desired new features has been improved.