Simona's place was fabulous! My friend and I recently stayed there mid February. The apartment was warm, clean, spacious, and trendy. It was just the two of us but the space would very comfortably accommodate 4 guests. Simona would check in on us to make sure that everything was going smoothly, which was extremely kind. She and her husband even suggested places around town to eat, shop, and have a good time. We enjoy walking, so the apartment was an easy walk to the Vatican, The Forum, The Pantheon, and any of the other staple tourist attractions. If you would rather take the transit, there were bus stops close, which made it super easy to get around.
My friend and I are a younger pair so we loved all the night life Trastevere had to offer. That being said, my only tip, is if you are the type of person that needs absolute silence and darkness when you sleep, then I suggest sleeping in the room closest to the front door, because it does get rowdy at night. I grew up and live in a large city so I slept like a baby, the noise at night didn't bother me. The apartment is on the 3rd floor, no elevator/lift, but we didn't mind that at all.
Overall, it was an amazing trip, felt like home away from home. We will definitely be contacting Simona again for our next trip to Rome. Ciao!