I booked for three nights on the dorm and I enjoyed it! Ernesto is very friendly and helpful, he explaind me how and where going in the city. The dinners were shared between people from differents countries, I had a really good time.
The flat is well located in Trastevere, not far from the city center.
Just a point: an little effort could be done on the cleaning in other to make this place perfect ;-)