I was in Rome for 4 days (3 nights) with my boyfriend and this apartment was perfect for what we needed.
The location is right in the hub of Trastevere in a small street right next to the night life. It can get a little loud during the weekend since it's pretty close to some bars/restaurants but if you're a heavy sleeper (or walk so much during the day that you knock right out - which is usually what happened) it's not much of a problem. The apartment is also under street-level with one big window that sheds light during the day, but we spent all day outside so it wasn't a problem.
Paolo and Daniele were very hospitable and wanted to make sure that we felt as comfortable as possible. We arrived pretty late but despite the hour, Paolo was there right on time to let us in and show us around (keep in mind that there's a $20 fee for people who come in after 22.00).
Overall, if you're looking for a place to sleep that's in the center of the city and hosted by a couple of locals, this is your place :)