We had a wonderful time in Rome and Marzia's apartment was perfect. It's located in the middle of Trastevere, a very lovely part of town full of bars and restaurants and tiny streets. Perfect for Roman nights out.
The apartment is spacious, tastefully decorated, and very clean. It offers wonderful views on the city. You can even see St Peter's dome. We didn't have a chance to use the deck (as we were there in December) but it seems the perfect place to relax.
Note that the apartment is on the 4th floor without an elevator and that taxis can't leave you right at the front door (most of the streets in Trastevere are for pedestrians only). Something to keep in mind if you have a lot of heavy suitcases.
I will definitively recommend Marzia's place to my friends visiting Rome.