When the camera's completely switched off, hit the power button and you'll go straight into camera mode which lets you shoot immediately, then about half a minute later the interface seamlessly goes back to smart mode, which is when you can hit the back or home button to toggle the Android unlock screen (though we'd rather go straight into the home screen).
The only interface customization you'll find here are the thumbnail overview of up to seven home screens (pinch anywhere on any home screen to toggle), as well as the "Pad Only" tab in the app drawer, the handy ASUS Quick Setting panel in the notification tray, and "ASUS customized setting" in system settings.