Location, location, location. This place is perfectly placed 5-10 minutes walking distance from Pantheon and Piazza Navona and only a 15 minute walk from the Colosseum and Roman Forum. And, every morning when you leave, you will pass the Largo di Torre Argentina, the site where Julius Caesar was probably killed and now home to a cat colony!
As other reviews have mentioned, it is really important to use the dehumidifier in the house. This place has history and, because you will be staying in an old wine cellar, you will have to use and regularly empty the dehumidifier. We emptied it 2x per day and, as long as it was emptied regularly, didn't have a problem. Staying at this place made our trip so much better!
Check out the restaurants on the same block near the Turtle Fountain--they are all amazing!