Zoomed-in photos will no longer look like crap
One major downside to the current iPhone camera is that its only capable of zooming digitally, so trying to capture something from afar gets you little more than a blurry, pixelated distortion. A dual-camera set-up fixes this issue by creating the potential for optical zoom, or the type of quality zoom you're used to with a traditional DSLR camera.
Finding a way to pack in the mechanics for this sort of zoom has been exceptionally difficult, since there isn't nearly enough space in a smartphone to accommodate the necessary depth of a traditional optical zoom lens. So instead, the images captured on each camera lens -- one a wide angle, the other a telephoto -- are averaged to create an intermediate zoom with no loss of resolution. This means you might finally be able to post Insta-worthy shots from the nosebleeds.