This apartment is a great value! It is well furnished, clean, and large for two people. It's very conveniently located. It's only a couple of tram stops away from Roma Trastevere station (an easy trip from Fiumicino). It's also a 10-minute tram ride from Centro Storico (and a shorter ride to the busier side of Trastevere, near the Tiber).
Federico and his staff were very helpful. When we arrived, there were already two liters of water on the counter, waiting for us, as well as a few different snacks, tea, and coffee. And communication was super easy, and while we never met Federico, we didn't really need to. He was always available via Airbnb, and quickly relayed messages as needed to his housekeeper.
The apartment is up on a hill, which is fairly steep walk. We got accustomed to walking up and down it very quickly, even though we're not in great shape. If you are in really bad shape, or have difficulty walking, you'll do better in another apartment (unless you don't mind paying for a hired car, which Federico would be very helpful in arranging).
There are a couple of things I wish I had known beforehand. One, the bed is uncomfortable. It is a very firm mattress, more like a futon mattress. I think it's fairly typical of Italian mattresses, so definitely not a deal-breaker. It was just rough for six nights.
And finally, you do not have access to a washer and dryer like the listing makes it seem. Federico's housekeeper will do your laundry for you, and will do it way better than you would do it for yourself (she folds everything so nicely!). However, she will only do one load -- either colors or whites -- for free. And a load is whatever fits in a medium-to-small plastic trash bag. Otherwise, it will cost you nearly 20 euros a load. I was a bit shocked by that. If your'e counting on doing a couple of loads of laundry during your stay in Rome, I suggest finding another location.