Fantastic location for first comers to Rome. This flat cannot be better located, you are within walking distance of all the travel spots, 5 - 15 min walks to Vatican, St Peter, Piazza Navona, Pantheon, Trevi, Steps, and many less landmark but fantastic areas. I was there with kids of 10-12 and we enjoyed being able to break the day and easily come back to this very central place for a rest. That way we made the most of our trip and saw so much of Rome.
OK you are in the central vibrant city center so expect a lively neighborhood as you are surrounded by bars and restaurants (do go to the Il Corello, 20m away, the Etabli, the fantastic gelato place Frigidarium, one of the best of Rome).
Finally, your host, Alessio is a lovely chap, eager to please and help, communicating wonderfuly, welcoming and who can arrange to shuttle back to the airport for a fee better than the usual taxi and a much more lovely company!