In iOS 7 iPhone Applications Are Automatically Displayed On iPad Non-Retina Screen
One of the subtle changes not mentioned of the iOS 7 is related to the system that enables the display on the iPad of apps made for iPhone, Apple improves the engineering and the graphics mode available in them.
Specifically, iPhone applications are automatically displayed full screen on iPad tablets that do not have Retina Display, Apple eliminates the option that allowed us to view in 1x/2x mode. This system is still available for the iPad tablets with Retina Display, but those without this screen automatically displays the entire visible surface of the applications, exactly as you see in the picture above.
Interestingly, on the latest iOS 7 beta users are no longer even presented with a 1x/2x toggle on non-Retina devices such as the iPad mini, and iPhone apps are instead presented simply as 2x apps taking advantage of Retina assets included in the app package.
iOS 7 automatically take all of the Retina graphics for iPhone applications and uses them to display applications dedicated to iPad tablets, even if they are made at a lower resolution. This system double the pixels anyway to display on iPad the iPhone applications, but if you look at the picture, you will realize that an iPhone app will look much better on an iPad Mini in iOS 7 than iOS 6. Changing the system is welcome, because now the quality of applications will be better and users will no longer have to choose between 1x mode, which displayes applications only in the center of the screen.