Horizon all but eliminates the possibility of accidentally recording a vertical video by shooting the video in landscape mode no matter how you hold the device.
The first time you launch Horizon, you're greeted with a brief tutorial explaining what each mode found within the app does.
Settings specific to the iPhone
Additional functionality is found in the iPhone app. You can do things such as add filters, adjust recorded frame-rate, and create custom settings.
The basic layout
There's not much to Horizon, aesthetically at least. A viewfinder is placed in the middle of the screen with buttons for settings, recording video or taking pictures, and one to toggle between front- and rear-facing cameras.
As you rotate the device, the viewfinder rotates in the opposite direction. This ensures your video is always recorded in a landscape orientation.
Settings within the app allow you to adjust camera resolution, change the zoom level, and replay the tutorial, to name just a few.