My friend and I stayed for 2 nights.
Before arriving, our host gave us clear directions how to get to the apartment from FCO airport. He then greeted us before check in time to allow us to store our bags, show us to our room, and to properly open and lock the doors.
My friend and I both felt it was a safe place to stay and was very clean. It was easy to get around with about a minute walk from the metro and within walking distance of the colosseum.
Great location, clean, and a friendly and accommodating host- I highly recommend staying here.