Filippo's apartment is world class. From the location, to the cleanliness and right down to Filippo's hospitality. If having your own view of the Trevi Fountain isn't enough, the location is ideal for getting around to most other attractions that Rome has to offer.
The apartment itself is beautiful and spacious with the bonus of two balconies looking out onto the Trevi Fountain. Most 5 star hotels would charge an arm and leg for that kind of view so Filippo's place is definitely good value.
Just be mindful that there is a long flight of stairs for those who might have mobility issues. Personally, it eased the guilt of having consumed one too many gelatos. We loved our stay and we hope to visit again one day.