Installing this protection on your pocket operator (PO) is an ambiguous experience. Not in the last because you need to remove the hinge from the PCB, which can mess up your board when not done appropriately. next to that, although meant to be removed by teenage engineering, the PO with the hinge has an own style... The protection could be cut on the top part to slide the hinge through, I did not do that, and I would guess it is not so easy to cut the good quality rubber.
The biggest plus I would call the somewhat more protection on the battery compartment (battery poles are covered).
The biggest minus is that the PCB screening is covered, which is normally different for each PO, and thus the functions must be remembered. Next to that the cover does offer slight, but not much protection for the PO display.