I think they look awesome.
You want to make sure IF you drop your phone there is no hard impact as it is made out of glass on front and back and aluminium.
With that "bumper" "case" if you drop it then it should absorb most of the impact.
Add in an invisible shield (or comparable) for that back and a power support
crystal protector for the front and you can keep your beautiful phone looking beautiful and protected against pretty much anything without needing a huge case.
It is a great idea... well done Apple!