Massimo was very kind and responsive. He greeted us personally and explained all necessary things about the apartment. We had to leave our suitcase somewhere between check-out time and our trip to the airport and he kindly offered to let us leave it there and hold on to the keys until we were ready to leave a few hours later.
The apartment is very nice, well-equipped and comfortable. Perhaps the only thing was the music from a neighboring apartment: not terribly loud, but certainly hearable.
Location is excellent, with the Colosseum right next door. A subway station is also nearby. You do have to take into account the great amount of tourists one block away, but that is now a constant all over Italy from what we saw.
Thank you, Massimo.