The apartment is very centrally located, walking distance from the Roma Termini, Colosseum, Trevi Fountain and Pantheon. I would suggest to the future guests to look very clearly on maps, where the apartment is located and how it looks from the outside, because it is kind of hidden in a side alley. Know some landmarks like the Windtre shop outside the alley, or the Molina's restaurant about 50 m away. By the way, I would highly recommend Molina's restaurant.
Another suggestions to the future guests is when you land at the airport and ask at the information how can we reach Roma Termini, they only tell you about the high speed Leonardo express train which costs about 14 euros per person and takes about 30 min to reach the Termini, but if you have some time, you can take the direct bus which only costs 6 euros and takes about an hour. Another option is the train which you have to make one change which is supereasy, and it will cost you 8 euros.