We had a wonderful time at Principessa Trevi.
Sara and her husband were welcoming and friendly. The apt was clean, spacious, comfortable and very, very central to everything that Rome has to offer.
30 seconds from Trevi Fountain, 10 minutes walk from the Pantheon. Everything, at the most, 30 minutes walk.
5 minutes from a great supermarket and transport links very easy.
Nothing to complain about - quite the opposite!
We'd definitely stay at the apt again!