Stop right now and book this place for the location. It was incredible! From the listing I thought it was IN Trastevere, but know that it is just CLOSE (incredibly close) to Trastevere. It's better though — you're in the center point of every Roman sight! It feels like there's a major destination in every direction from Piera's place. I went on a little walk my first night and accidentally ended up at Piazza Navona, which was a sight I had wanted to see!
I booked Piera's place because of all the reviews raving about the location — let this be one more confirmation. You're a short metro ride away from the Vatican and the Colosseum and within easy walking distance of the Spanish Steps, the Trevi Fountain, the Jewish Quarter, Campo di Fiori, and Trastevere.
The room itself is simple and gets the job done. My only complaints are the pillow was uncomfortable and the bathroom didn't smell too great. It's a shared apartment, so there are other renters there too but I hardly saw them. You're next to a busy street, so I was happy I brought my earplugs but you can survive without them, too.
Her mother checked me in, which worked out fine but I speak no Italian and her mother speaks no English. I'm lucky that a fellow renter was there who spoke both and she translated but that was an unexpected start. But there's really not much you need to know besides using the key to unlock the front door — basically all she was telling me was to put the key all the way in instead of partway. Simple enough!