This is my favorite place to stay in Rome, a really lovely sun drenched apartment with evocative views of the distinctive and lively local piazza below, high ceilings, book filled walls, and the best location (in my opinion) in all of Rome. I have stayed at least five times previous and would love to keep coming back. The kitchen is simple but equipped with just what you need, the bathroom is spotless, and the flat is convenient to nearly every attraction in Rome. Moreover, it's a spot that has a very local feel, in spite of being in a quite historic area.
It's very close to major attractions like Campo de Fiori, Piazza Navona, Pantheon, and The Vatican. In fact, it is also within about 5 minutes of each of the historic locales in which the opera Tosca takes place (The church of St. Andrea Della Valle, Piazzo Farnese and Castello St. Angelo). It is one block from a beautiful stretch of the Tiber ("Tevere") River. All that one needs is within a couple minute walk: grocery store, wine store, bakery, coffee bar, and some of the best wine bars and restaurants in the City. There is a nearby taxi stand and bus stop with a direct bus to the main train station (Termini) and St. Peter's.
Costanza is quick to respond, kind, and leaves soap, shampoo, as well as a very nice selection of towels and a city map marked with the apartment's location and other sites. This is really the greatest place.