Jump to the best parts of apps via a shortcut menu
You know all those default iPhone apps? Here's a trick to get rid of the ones you don't use. But for the ones you actually like, if you press and hold the app icon, 3D Touch activates a quick shortcut menu so you can jump straight to the most popular or useful features. For instance, pushing down on Messages or Phone pulls up the names of frequently messaged or called contacts. Notes, Mail, Maps, and Calendar all have nifty shortcuts too.
A few third-party apps are also in on the action. Facebook, Instagram, Spotify, Twitter, Slack, Yelp, NY Times, and more all let you press and hold for quick access to their best features. In my experience, the app that's best served by this sort of quick-draw access is Shazam. You can quickly figure out what song is playing without even opening the app.