It is a smooth ROM, it brings the Chronus cLock widget, support for customizing the software and hardware buttons, customizable navbar ring, navigation bar widgets, notification power widget, status bar mods, theme engine, quiet hours mode, volume rocker music controls and multiple others. (android.gs)
To get started, head to the Download section in your Xposed Installer app, then search for NavBar music visualizer. (android.gadgethacks.com)
The site says that it remains unclear whether all Android N devices will get the new navbar buttons (old Nexus hardware included), or whether the design change is restricted to this year's Nexus devices. (bgr.com)