And having no safety railing around the perimeter, it would be wise to not let Granny (or any aging friend/visitor/relative) out there very long, unattended. It's an accident waiting to happen.
I'm speaking from experience. My 80-year-old mother stepped off my back patio (9" above the lawn), fell onto the grass and broke her hip. She was never the same after that, even with the stainless steel hardware they used to fix the fracture.