We loved our stay in Trastevere, and would definitely recommend booking this apartment.
The place is exactly as pictured: very tastefully decorated with a traditional Roman ambiance. The apartment is on the third floor of a four floor building, and while the street below can get a bit busy in the evening, the double-paned windows blocked the sound really well. We had no trouble sleeping at all. Also worth noting that the AC works really well, with a separate unit in each bedroom. We stayed in Rome in June, while it was +35-40c out, but it was nice and chilly inside.
The location is perfect, at the heart of Trastevere with an easy walk to Vatican, Piazza Navona, and the Colosseum. There is a nice sandwich shop downstairs, a cafeteria, and several great restaurants. Would definitely stay here again!