My adult son and I spent 7 nights at this apartment. It took us a few days to realize what a great neighborhood we were in but when we did we found that we were immensely pleased with the bars, restaurants, and shopping here (recommendations below).
The apartment itself is perfect for a couple or for a solo traveler. The street it is on looks, initially, not very charming but it proved to be fine, very quiet, and we never felt any danger or discomfort approaching or leaving.
If you have 2 travelers, not sleeping in the same bed, Luca (the host) will arrange for a spare bed. This works fine though it makes the apartment very cramped with little room (other than the beds) in which to relax and also very little room for luggage. For this reason, I think the apartment is best for 2 people who will sleep in the same bed. The bed is big and comfortable and there is good lighting (from light fixtures) in the apartment.
The shower is possibly the smallest I've ever been in and the water in the bathroom is easily regulated but can be scalding if you aren't careful (so be careful).
The patio was not of much use for us given the weather, but I could imagine it being very pleasant during the heat of summer. It's quite large and nice, with table and chairs.
One of my favorite things about renting from Luca was his responsiveness. As a host, I found that all I had to do was send him a note through the airbnb app and he was quick to respond and act. I had no phone service the whole time I traveled so knowing I could reach him easily in this manner was great. Check in went perfectly and the wifi in the apartment is excellent.
Recommendations: Ai Tre Scalini (drinks/food), La Boccaccia (cheap, great pizza on Via Leonina, the weekend Mercatomonti (clothes/gift shopping), and Piazza della Madonna dei Monti (people watching while sipping wine on the steps of the fountain).