As someone with an interest in photography, this seems like a really interesting idea, but one with potential issues. One of the reasons I picked up a digital camera was to get optical zooming lenses. Since getting one I changed mindset and actually adopted a fixed focal length camera but that is beside the point. The ability to optically zoom is a great advantage for a camera and this looks like a clever way to add this feature in a small compact design.
However, there is still a moving component required in this design even if it would move at a different angle and not bulging from the front of the phone. Perhaps this would occur in the body of a phone and it certainly seems this is supposed to be more compact but I’m not certain this would be desirable for Apple as it would take up vital space in a phone body.
Still, adding a say 70mm equivalent lens to the 31mm (aproximately) focal length already found on the iPhone would add some nice benefits for people who enjoying taking portraits with an iPhone (yes they are a rare bunch) plus the addition of a second camera can add artifical bluring options to create a bokeh like effect (as seen in some android phones like the HTC One m8)
This won’t be the same quality as using a standalone camera but it would still be a step up with lower distortion. It’s certainly something to keep an eye on with the rumors of a two camera arrangement in the iPhone 7 plus/pro.