We had a great experience at Sveva's
She was kind enough to wait for us when we were arriving late and she gave us great recommendations.
The place is well equipped with everything you might need and the bed was very comfortable. The noise from outside, while it can be heard from the living area, it is not from the bedroom.
We used the washing machine which really helped us and cooked breakfast every morning.
The location is very nice, right in Trastevere and walking distance from mostly anything. We also used the Tram quite often which runs just a few blocks away.
The only thing is the wifi didn't work very well but as we had internet on our phones we didn't bother to ask.