I stayed in Apartment 7.
Positives:
The apartment was very well equipped, it has a washing machine, ironing board etc which was very good, everything that you would need.
There is a small lift which is good for luggage.
The room was clean, there is a very large clean bathroom
The location is good, a short walk to Trevi fountain, Piazza Navona etc
There are a couple of shops nearby for groceries etc.
Negatives:
Do not book this, if you need decent sleep. The upstairs neighbours ruined this for us as they were coming and going at all hours and making no effort to be quiet (2 am etc), and it sounds like their lounge is over the bedroom, even with ear plugs it woke us up.
The layout of the room means that the apartment door opens into the bedroom, so all noise from outside disturbs your sleep, such as slamming doors, the lift doors which are old and metal and make more noise than you think.