In simplest terms, this stuff is a metal with an amorphous structure. That is, it's atomic structure is 'random' rather than the ordered crystalline atomic structures (think of cubes and lattices with atoms at the nodes) metals usually take.
It flows better than 'normal' metals which means it can be more effectively moulded and cast. This means you can cast a complex shape that would usually have to required machining to form in a traditional material. A big advantage in manufacturing.
The disappointing thing is that they've only used it on the bezel, rather than demonstrating it's 'real' properties, such in a complex metal part like a case.
Given that the result will look like any other case, and only the manufacturer gains from having fewer processes (plus it wouldn't be cheap compared to stamping and machining the current cases)...I don't blame them.