Gesture-based feature lets you preview notifications and other info without waking up the phone
The Samsung Galaxy S4 is one of the most feature-laden phones we've ever used, and it's easy to overlook some stuff, especially if you don't go digging in menus. One neat but understated capability of Samsung's new high-ender is its ability to detect gestures at a distance using front-facing sensors, even while the device is sleeping. The GS4 takes advantage of this capability by introducing "Quick Glance," which lets you preview the time, date, notifications and other details without waking up the phone.
Part of the Air Gesture suite of features, Quick Glance can be activated by long-pressing "Air Gesture" in the quick settings pull-down and enabling it in the list that appears. That's also where you control other gesture features like Air jump, Air browse and Air call-accept. (Yeah, this thing's not short on gesture controls.)