In theory, Haptic Touch can allow you to do certain things quicker than you’d normally be able to. If an app is supported, you can hold down its icon to produce a menu that will immediately take you to a specific window within the app, for instance. With 3D Touch, you previously needed to press your finger pretty hard into specific app icons to get the desired result; now, all you need to do is hold your finger on an icon until the app activates or produces a window with options to choose from.
The torch icon and the camera icon on the lock screen, for instance, now open with a long press rather than a hard press on any Haptic Touch-enabled iPhone. You can also hold down the space bar on the keyboard until it becomes a track pad that allows you to scroll back and forth through any text you’re currently typing.
To customize the length of time you need to press your down before Haptic Touch kicks in, go to Settings -> Accessibility -> Touch -> 3D & Haptic Touch. You can toggle between Fast and Slow in the section labeled “Touch Duration.”