ProShot has options for 4:3, 16:9 and 1:1 aspect ratios allowing the shooter to choose what best suits their intended shape. It also has support for custom aspect ratios, so 3:2, 21:9, 50:3, and more are all possible.
On devices with Camera2 API support (currently LG G4, Nexus 5, Nexus 6, Samsung Galaxy S6/S6 Edge), ProShot offers full manual control over ISO, shutter, white balance, and focus, in any mode, even during video recording.
ProShot requires that the Android OS is on version 5.1 or higher in order to install and work. Considering there is only a developer preview for this version to date, it basically can not yet be installed. Even when 5.1 comes out there will not be many devices using it. Developer's note: there