Giulia's studio is in a perfect location - you actually have a view of the Trevi Fountain from the front of the building. The street the apartment is on is VERY busy but thankfully you can hear no street noise at all once inside! There was a little noise from the neighbours but otherwise we had absolute peace and quiet. The apartment is very clean, had all the amenities you'd expect. We found several wonderful restaurants literally right outside the front door (I recommend Il Chianti).
It was a good central point to be able to walk to Vatican City (half hr walk but plenty to see along the way) and Colosseum (20 minute walk).
Giulia did offer a transfer service which I now wish we'd gone for as the bus from Ciampino took 40 minutes (with another 30 minutes on top of that to walk to the centre of Rome) so we ended up getting a taxi on our return journey to the airport in the end!