My girlfriend and I stayed here and absolutely loved the apartment. It is ideally located and easy walking distance to Navona, the Pantheon, and just a bit further to the ruins. We especially loved being able to walk to Campo dei Fiori in the mornings (literally about a two minute walk down Cappellari), pick up ingredients at the market, and cook our own food in the evening, which added a certain touch of authenticity to our time there and helped save money that we could then use to go out.
The apartment itself was excellently maintained and even included a washing machine (very welcome after two weeks on the road). We noted that the bed in the bedroom was slightly uncomfortable so we slept on the futon out in the living room, which was great.

We really loved hanging out the windows that looked out on Pelligrino and Cappelari and watching the local merchants and visitors.

A tip for the neighborhood, DON'T waste your time in the actual Campo for drinks or dinner. The places there are all overpriced and the food was remarkably lousy. Instead, if you need to stay in the area, cross Emmanuelle and try that area (avoid The Abbey unless you're homesick for some dumb drunk American chicks or bros with popped collars). An example of the difference, two espresso, two cappuccinos, and two croissants on the Campo, 15 euro. On the other side of the street, 3.40.

On the morning we were leaving, Federico arranged to have a (very nice) car pick us up and take us to the airport. Great host.

We will certainly try and book this apartment again on our next trip.