Screen Recording
One of the best surprises of iOS 11, Apple's new Screen Recording feature could easily be overlooked if you don't where to find it. Existing only in the Control Center, it allows you to easily capture a video of your screen (and yes, it does make it easier to covertly record Snaps).
As part of Control Center, Screen Recording is fast, easy and reliable — something that can't be said for third-party apps or Apple's previous method that relied on QuickTime on a desktop.