The apartment is cozy and private, and great for two people! I stayed with my mother, and both of us were pretty satisfied with the place. I didn't get a chance to meet Nina, but she was super helpful and always available through text. She even arranged for a private pick-up from the airport for my mother, who was traveling alone.
The only problem I faced involved the apartment's proximity to the termini. Getting to termini requires one to take a 25-minute tram and then walk for another 5-7 minutes. While this isn't a huge issue, the fact that public transport doesnt run all night made it slightly inconvenient for us to roam around at night, since the last tram back to the apartment was at 11:30pm. If you're okay with the travel, it's a good place to stay at.