We enjoyed our four days in Rome very much. Ernesto was a welcoming host, and everything went as planned. We stayed at the "Black Swan" room which was as described, and the shared bathrooms worked for us. The location in Trastevere was great with walking distance to everything from restaurants, cosy streets and sights.
The only minor flaw for us was the not sparkling clean bathroom and the dust/waterbottle/pen under our bed. All in all we would definately recommend Ernestos place if you are looking for a nice room in probably the best area in Rome.