My daughter and I stayed in this apartment July 2018 for eight days. It is very conveniently located, in particular to the Pantheon neighborhood and Piazza Navona. The Spanish Steps and Trevi Fountain are an easy 10-15 minute walk. The apartment is near several convenient bus lines including #492, which takes you to the Vatican and #87, which takes you to the Colosseum area. There are multiple other bus lines with easy access while the nearest metro station is 15 minutes from the apartment. We bought a week long metro pass given the length of our stay, which worked well.
In regards to the apartment, it is great as long as you are comfortable with stairs. It was very clean and Pietro and Valerio were very accommodating to our needs. They even bought us a much needed coffee on our arrival day.
Air conditioning is present in the bed rooms. The kitchen was adequately stocked with cooking essentials and a supermarket is a 5 minute walk away. The apartment comes with a washer and drying rack. Bring your own detergent or buy at the supermarket. The neighborhood feels safe and has an active night life but the apartment is located on a quiet street.
Overall, we would highly recommend the apartment if you are visiting Rome.