Things I really liked -

1. great location
2. restaurant downstairs (http://www.osteriabarberini.com/) is AMAZING and very reasonably priced.
3. the flat is used mostly for guests, people do not live there. this makes the whole stay more comfortable and many amenities (towls, bed sheets etc) are very guest-friendly

overall -
a great location, short walking distance from Spanish Steps, Trevi Fountain and the Barberini Metro station which connects to the vatican/Termini station.

Manola is a truly great host, helpful and open-minded. reacts quickly and always reachable. the apartment is just as advertised, a very comfortable kitchen and bathroom.