I stayed at Giacomo's place on my own for 3 nights. Unfortunately, I have not met him, only his roommate, Yuliya. Still, Giacomo sent me great recommendations and made sure I was alright.
The check-in was flexibel, they let me to arrive earlier and drop my luggage there in the morning, which was great.
The air-conditioned room is big enough for 2 persons. The flat is quite central (by foot 30-35-40 minutes), however after a while I rather took the bus because it got tiring to go back and forth (bus stop 170 is 2 minutes ago).
The Vatican and the San Lorenzo area are rather far away, so you definitely have to take a bus to get there.
I enjoyed my time in the flat, so I would recommend it.