The new Design tab
Document formats can be further extended by choosing Themes, Colors, and Fonts to use with them. If you come up with something you’d like to use all the time, the new Set as Default option allows you to make the current combination of formatting settings the default for all new documents.Word 2007 and Word 2010 added interesting features for styling a document, but the tools were scattered throughout the user interface, and they were difficult to use. The new Word 2013 Design tab consolidates all these tools onto one tab, so they’re easy to find.
I've been a loyal MS Word user for a couple of decades. However, I'm using Word less and less.
Upgrading to the latest version doesn't make sense for me. The above article outlines 10 new features.