My mother, 5.5 month old son, and I spent 9 nights at Dario's lovely apartment. We had a wonderful stay.
The apartment itself is very large, clean, and well appointed, with lots of light and beautiful views over Rome. I have stayed in many Air BnBs and this contained some of the best equipment - good quality pots and pans for cooking, a very nice hair dryer, lots of glasses and plates, etc., making it easy to cook. During the day you may hear lovely music sounds coming from the neighbouring symphony, but the apartment is EXTREMELY quiet at night. The beds are very comfortable, with lots of blankets and pillows. Nothing was lacking.
Dario was extremely helpful, arranging for our airport pick up and bringing all our bags to the apartment when we arrived, as well as separate airport transport for my mother and I on our returns.
The location is truly incredible - we walked all across Rome (even to the Vatican), and were within a 10-20 minute walk of Piazza Navona, the Pantheon, and the Borghese Gallery, and of course less than 3 minutes to the Spanish Steps (and the Spagna metro station). I have previously been to Rome but had never stayed so centrally, and I now cannot imagine staying anywhere else.
As the description states, and other reviewers have noted, the apartment is on the 4th floor with no lift, and so I would not recommend this for anyone with mobility issues or handicaps, but my mother and I did not have any problems. The stairs are safe and well lit, and not too steep, and I was never nervous carrying my son. It is well worth it - the views are spectacular!
I would also note that the second bedroom is not a true bedroom, with a door that closes, but is in a large open room between the kitchen/dining area and the master bedroom. This worked well for us, but for two couples or for groups or families wanting more privacy this could be an issue.
Finally, after checking out I received a message that Dario's housekeeper had found a missing earring that we had lost, which was quite valuable, and we had scoured the apartment for. This speaks both to the honesty of Dario and his housekeeper (we had not mentioned the missing earring) and the thoroughness of the cleaning of the apartment after each stay.
I would highly recommend Dario's apartment, and would happily stay here again.