We've had a great stay at Simonetta's place.
The apartment itself is located quite close to St. Pietro train station, so getting there from FCO takes just one train stop. Easy. There are a couple of convenience stores nearby, including a 24/7 Carrefour one (wow). A couple of super local cafes/bars are around as well, so breakfast is not a problem either.
This apartment is close to the Vatican, but a bit further away from the other parts of Rome that you might be interested in. This was not an issue for us, as we were okay with walking a couple of kilometres, plus you can always take the bus.
The communication was swift and easy. Check-in / Checkout was simple as well. I should note that the apartment was VERY clean, which is a very welcome trait. The sound insulation also exceeded my expectations.
I'd say that the only real thing missing was a proper AC in the master bedroom, the fan was just barely managing to keep the heat away. But we were staying in this apartment during a heatwave in Rome, so this probably does not apply on a regular basis.
There were enough amenities and we were never feeling that we lacked anything during our stay.
TLDR:
– Good location
– Clean apartment
– Good sound insulation
– Close to shops/cafes/bus