Some nice features :
-You can arrange the shortcut icons in pull-down notification panel.
-Use two fingers to swipe down , to get all the toggles at once.
-Long press menu button to get Google search (when you are in homescreen/widget screen)
-Use volume button to adjust size of font in messaging app
-Long press toggle to directly go into its settings (like long press wifi or BT etc.)
-Multi-window is cool thing to try (watch youtube videos to know more about it)
-Air View is good when browsing (There are lot of options inside Air view , activate webpage maginifier)
-You can use the green icon on "Internet app" to activate reader mode and you can activate night mode using menu key
-Pinch to zoom out of the widget page or app drawer
-Blocking Mode , Driving mode are good too (try them once)
-Use voice commands like "cheese" or "smile" to take pictures
(There are so many , I just mentioned what came top of my head)
refer to this video :
You can mirror your Galaxy S4 songs , photos to your Samsung TV if you have both TV and phone connected to same wifi network.
edit : Can someone tell me what wallpaper that guy is using ?