What a lovely apartment! It is a fantastic location. A short hop to the Castel Sant'Angelo and the Vatican. Perfect if you want to walk to the main sights, perhaps less good if you want the Metro because it doesn't reach the historical centre. Bus links are great from Corso Vittorio Emanuele II, which is extremely close. Via dei Coronari is very close and beautifully atmospheric.
The apartment itself is spotlessly clean and very quiet. It was perfect for our family of four. It is not as light and bright as the photos suggest, apart from the sitting room and kitchen, but it didn't bother us.
NB As the listing suggests, to get to the apartment you have to climb up several flights of quite steep steps. Perhaps therefore not ideal for those with reduced mobility.