This apartment is gorgeous and very well-located, and Lavinia is an excellent host. We were within walking distance to not just the lovely Trastevere neighborhood and all it has to offer, but also to the Jewish Ghetto and Regola neighborhoods as well as the Roman Forum area. Public transportation in the area can be tricky (no metro station, just buses and trams), but it's very walkable.
The apartment itself is lovely: the kitchen is well-equipped, the living room is clean and cozy, and the bedroom is spacious and had the comfiest bed we slept in during our entire trip to Italy, as well as a walk-in closet. We didn't get the chance to use the balcony, but the views were lovely.
Lavinia stayed late to meet us at check-in on the night of our arrival - we had some difficulties with our rental car drop-off because of course we did - and even though she had plans for her birthday, she made sure we were set up for success by taking us through the apartment room by room and showing us her binder of local tips. Of those, we tried Mr. Clood, Suppli di Roma, and Tonnarello, all of which were amazing and within a 1-5 minute walk of the apartment. The gelateria across the street that you can see from the balcony wasn't in the binder, but it was also very good, if a bit pricy.
The only con I can think of is that the toilet is a bit finicky and it can take a few tries to make it flush, even with nothing in it. Seriously, that's it. Everything else was wonderful, and I would recommend this place to anyone looking to stay in Trastevere or Rome in general.