Previously, you would see the word count only for the document currently being edited. Now, you can select to include multiple documents in a Total Word Count, which will appear right next to the current document's word count. This should be very useful for writers (like me) who use a separate document for each chapter of a manuscript. Now I can see both the word count for the chapter I'm working on, and for the manuscript as a whole.
I hope that you find this new feature useful. Enjoy!