What makes the app work is the gyroscope on the phone and the tablet. The app supports the Apple iPhone 4s and higher, and the third generation Apple iPad or higher. For all of the supported devices, resolutions of 1920x1080, 1280x720, 640x640, 640x480 and 480x480 are available. For the Apple iPhone 4s and the Apple iPad 2, only 640 x 480 and 480 x 480 are available.
The app also supports aspect ratios of Square 1:1, Wide 16:9 and Standard 4:3. It also comes with 8 'fun' filters and allows you to share your photographic masterpieces through your favorite social networks. And yes, the app can be disabled just in case you are tired of the horizontal orientation. If you're interested in Horizon, you can learn more by clicking on the video below.
source: Horizon, TNW via Slashgear