Navigation in the new site will have a few benefits over the old system, but will have a little less flexibility. In any site directory there is a navigation file: _nav.inc. This file holds your navigation items. Similar to the old system this is done with an un-ordered list. The simplicity of the navigation include file helps create a uniform look for navigation for the site.
You must always publish your _nav.inc file after a change to the navigation structure!
Automatically Generated Features
One nice thing about the navigation is that you don't have to edit the navigation file to add your new page, that is done automatically! Also, if you add a new sub-section to your site, that will also be added to your navigation. You do have to publish your _nav.inc file(s) after any change has been made to make sure the live site navigation is updated.
The new navigation will also include the navigation of sub-sections in your site if you choose and allow users to view those sub-pages easily. Sub-sections will have the page title of the sub-section's index page and a gray down arrow next to that name that will signify that there are pages under this section. Clicking on the name will take the user to that sub-section index page, clicking on the arrow will expose the sub-pages of that sub-section.
While you can add and remove links, there is no option for adding special content to the navigation. This would include images, separators or adjusting the look of the navigation items. The left nav area is only for navigation. Anything you want to showcase or single out should go in the right column, if that is turned on.
Currently if you are in a sub-section and add a link to the parent page, you will get recursive links (they will keep repeating). To solve this, edit the link and choose the class title No Sub Nav. This will keep the recursion from happening.