Overall a good stay. Very friendly and responsive hosts - we were greeted at check-in and offered free cleaning during our stay (we stayed 9 nights). The location is fantastic, right next to the river and the lively Trastevere neighbourhood and within walking distance of everything.
Our only surprises were the size of the apartment and the noise. The apartment is right above a popular restaurant which closes between 12-3am depending on the day of the week so it gets very loud. We were also expecting to have a kitchen with some space to sit and eat; however it's too tiny to cook and there's no table for eating. The bathroom is also very tiny and narrow.
Other than this, it's a good place with great, professional hosts.