Fernando made us feel very welcome. We had very good communication leading up to the trip and on the day we arrived. He helped us with our bags, showed us everything we needed to know about the flat and gave us useful a overview of local shops, bus stops, how to use the public transport and some suggested routes around the city. He was kind enough to provide a beautiful bowl of fruit and some other useful groceries. He even helped navigate me back to my car rental return and helped us with our trip back to the airport.
The flat is very comfortable, and very spacious. It has traditional features like the beautiful patterned stone floors, but also all modern conveniences (a very new kitchen with a big fridge/freezer and dishwasher, a spacious bathroom with washing machine/iron/ ironing board/clothes dryer). The WiFi appeased the children. We really appreciated the air con as we visited during a hot August.
The location is excellent. First, it was practical because there were several coffee bars, shops and restaurants in the adjacent streets (including maybe the best gelateria ever!) as well as a large supermarket 3 blocks away - easy walking distance. Second, it was practical because the central sites were all within walking distance (we did use public transport a few times but mostly because of the heat).
We arrived in Rome in a rental car and were able to park outside while we off-loaded luggage (for driving in to Rome I'd recommend coughing up for some phone data and using phone sat-nav. We tried without but got tripped up by a couple of confusing road junctions and some networks of one-way streets).
It's perfectly feasible to walk to the flat from Termini, but not recommended if you have lots of luggage or if it's particularly hot!