The apartment in Piazza Navona was very nice. They have refurbished a top floor in a historic building overlooking Piazza Navona. The location is superb for a stay in Rome.
The apartment is well equipped, particularly the kitchen, and it has terrific views towards the Piazza. For comfort, the apartment has an elevator - super convenient when you have to move luggage or groceries for a big group of guests.
The two rooms in the upper floor lack a little bit of space, particularly if you carry lots of luggage and/or if you are a tall person. Be aware of that and be patient.
A truly nice apartment that you should not miss if a stay in Rome is in your plans, giving its excellent location and views.