The apartment is located at walking distance to Roma Termini station, very convenient if arriving to the city either by airport train express or Regional train. The Repubblica Metro station is even nearer to the apartment and therefore it is very convenient to get into Rome city center and also Vatican city by metro.
Also Simone is very friendly and helpful as he provides some suggestions when I was planning the trip, and also answer to our questions almost immediately when we were in Rome. He provided a cell phone and it was very useful for making local call such as calling for restaurant reservations or confirming the tour.
There is market right outside of the apartment early in the morning and making some noise, however it has no problem for us as we were waking up early.