The iPhone X has a taller, narrower 5.8-inch, 19.5:9 screen with a "notch" at the top and many third-party apps just can't deal.
App developers need to get an iPhone X to see if their apps work, and make the appropriate changes, if necessary. It's already starting to happen; Google Photos, for instance, was updated for the new screen size today.
So far, we've seen three different kinds of app failures: severe letterboxing, messy UIs and app stability. But it's not all a disaster. These 10 developers are on the ball, and they're bringing you apps that look great on the iPhone X from the start.