The app is pretty stripped down but shows some absolutely tremendous potential.
The tremendous potential would be harvested if Canon would release an sdk for the wifi control so any 3rd party software could control the camera beyond basic p&s - but knowing Canon they are too conservative for that or will only enable it for the 1dx2... let the reverse engineering begin!
Unless I want to be a spyier, WHY do I want to operate the camera through a cell phone
Wildlife shooting comes to mind (and Canon also suggested this) - put some baid in front of the camera and keep a safe distance either from shy or deadly animals... or for an event put the camera somewhere high and get shots no one else can. Of course in all these cases you have to know where your subject(s) will be when positioning the camera or put the camera on some other remote-control gear.