Sandro's apartment is well located (only a few hundred meters from the Vatican Walls and only a little further to St Peters) with plenty of restaurant options and easy access to the train station, so getting to the major attractions is very easy.
We didn't meet Sandro (his partner let us in) but his communications were prompt and thorough.
The apartment itself is well suited for two couples, with large bedrooms, a well-stocked kitchen and very comfortable living area.
There are two things that need to be improved to make the apartment perfect. Firstly, the lack of wifi or standard internet connection is a little inconvenient, when you consider how cheap it is in Europe. Adding this would make a big difference to a traveller's experience.
The second is the bathrooms - both showers were very poor, with little water pressure and not enough hot water. Also, a little more attention to the cleanliness is needed.
Aside from these two things, we had a great experience staying in Sandro's apartment, especially for its proximity to the Vatican.