Do you have plenty of enabled Unknown Sources in your Security settings (we all do, or did), install the APK, hit home and choose Nexus Launcher. When you long press there’s a settings menu that includes a ‘Show Google app when swiping left’ option as well as options for screen rotation and app suggestions at the top of the app drawer.
In addition, there’s a really cool new widget picker but still being worked on is the rumored Calendar shortcut when tapping the date up top. Some have noted that this widget force closes when trying to select a new wallpaper, but can easily be fixed by flashing the zip via TWRP. Flashing the zip will also enable the swipe right for Google Now action.