We stayed here with our two children for seven nights, and I'm so glad we did.
The location cannot be beat if you want to be close to restaurants, and it was convenient to walk to many locations, including Piazza Navona, the Pantheon, Campo di Fiore, Trastavere, the Spanish Steps, Trevi Fountain, and Castel Sant'Angelo. It was also easy to take the 81 or 87 bus to the Colosseum/Forum/Palatine Hill area. We really enjoyed eating nearby at Il Corallo, having a cappuccino and croissant at, ironically, Rome Beer Company in Camp di Fiori, and getting gelato at Gelateria del Teatro (though Frigidarium and Giolitti's were both good as well).
Maria had the apartment set up as two bedrooms for us, with the second bedroom having a pull-out sofa. The rooms don't have doors, but it worked fine for us with the littles. One of the restaurants (I assume) nearby was playing dance music until about 10-11pm on most of our nights, and one night we could hear a particularly boisterous group of diners. We were able to sleep fine, though, and figure the noise goes along with the excellent location. The second (middle) bedroom did not seem to be noisy, and the back patio was a quiet retreat.
Maria was kind enough to provide a booster seat for our youngest child without us asking. She also arranged airport transfers for us both ways. She was so responsive to any question we had. We really appreciated her hospitality and the opportunity to stay at her place.