Stayed at the apartment for two days/nights. Everything was as described - clean and in good shape, and the owners were helpful and responsive. The two main rooms both have comfortable beds with additional sleeping available on a pull-out couch, and I think we saw an additional cot in the closet. Not a complaint, but there is not much of a living room since that room is the second bedroom. (There is a couch, bureau, window seats, and TV along with the bed.) The workspace is a small table in the room/hall space off the kitchen and bathroom at the back of the apartment. The kitchen had everything needed (pots, pans, cups, plates, silverware, small coffee pot, small fridge, etc.), and there is a good market just steps down the street. The bathroom had a small but good shower. We also appreciated a drying rack for clothes in the closet off the kitchen so that we could do some laundry.
The location is excellent - 5 minutes from the Spanish Steps (and Metro stop there), 10 to Piazza del Popolo, 15 to the Trevi Fountain and Pantheon. Steps from lots of shops on the Via del Corso, yet the neighborhood is quiet for sleeping at night. (The apartment also is situated next to a music school, so there is lovely music to enjoy when you're sitting on the small terrace - nice view of parts of the city.)
As reported in other reviews, there are stairs. Just over 100 of them. But they are grouped in short flights, they're not steep, and there are spots to rest. We were prepared for them, so they were fine. We just tried to minimize our comings and goings so we didn't have to climb them more than once or twice a day.
All in all, highly recommended if everyone in your party can handle the stairs.