The location is amazing. Less than two minutes from St. Peter's basilica. You can see the dome and the Apostolic Palace from the master bedroom. It's on a quiet side street, right next to the Passetto di Borgo.
The flat itself is exactly as described and photographed. The master bedroom was the main attraction for me with its view. I can't find much fault with the kitchen and bathroom - there is a step into the bathroom to watch out for.
The hosts were fantastic. They met us in the flat, gave us a brief tour and provided a list of restaurant recommendations (I'd definitely recommend Vii Coorte from the list). They also provided a map and pointed out the main attractions.
Overall, it was a really pleasant stay. I hope to book again soon.