If you are looking for a central location in Rome, LOOK NO FURTHER! We walked everywhere: Vatican City -25 min, Pantheon -3 min, Ancient Rome - 20 minutes, Trevi Fountain -15 min... even Borghese/Spanish Steps (about a 40 minute walk, but stop for lunch on the way!). The apartment is beautiful and secure. It's located in a safe neighborhood that is close to tons of restaurants (About 5-7 minute walk away). It is very well equipped with all you will need for your stay. There is a grocery about a block away to get anything else you may need.
Carlos did not meet us at the apartment but was incredibly responsive leading up to arrival. He had Filipe meet us there who spoke fantastic English and gave us the tour of the apartment and tips for visiting Rome. We even got a few restaurant recommendations which were great!
My only thing to consider is if you are someone who likes LONG hot showers, the hot water tank is a little small (especially from what we are used to in the US). Filipe was careful to point that out to us during our tour, so we adjusted our bathing times accordingly. No problem!
Definitely try this place out if you are looking for a unique "home base" that is centrally located and absolutely beautiful!