About host: Alberta and her daughter Francesca were very kind and considerate hosts. They picked us up at the termini station to the bnb. And we didn't know that the laundary doesn't working. Alberta washed and dried our clothes by herself for our baby. And Francesca recommended us the very nice restaurant, bar and even modern art museum. Many thanks to them.
About bnb: at first, we a little bit disappointed because it was too small. When I saw pictures on the website, I thought it might be a spacious one-room. It's not that big enough. But if you don't have a kid, and you are young guys, it may not be a big problem. There also are a bathroom and a small kitchen.
About accessibility: it's nice. you can get to the main tourism places like Colosseo or Batican city by bus n.81. And you can take a bus n.105 to the Termini station.
About neighborhood: I felt not that dangerous. Rather, many people in that town welcomed and helped us. And there are supermarket, pharmacy, many restaurants and bars near bnb.
It was very happy trip to Rome :)