I had a great stay at TiberHaus.
You could not ask for a more considerate and helpful host than Gianni and the apartment was spacious, comfortable, clean, and equipped with everything you need, and lots of nice touches, like a map of the area with local landmarks, a board with useful phone numbers and a book with sights and services.
Rome was experiencing the hottest weather in over ten years when I arrived but the air-conditioning handled it very well and the apartment was always pleasantly cool.
The neighbourhood is peaceful. There's a good supermarket just a minute or two away on foot and the location is also great for Trastevere, Piramide, trains for trips to Ostia or for getting to and from Fiumicino, and not far from the Circus Maximum and Colosseum.
Highly recommended!