Sergio's place was lovely, really an oasis in Rome. Our room was spacious with a big double bed, our own balcony (which was amazing to have), and our own bathroom, with all new fixtures. It was very clean and tidy, and the location was great - in a residential area, about a 20-minute walk from the Vatican. Sergio was very communicative, and though we did not get to meet in person he made sure we were very well informed about everything we needed to know. He also left some great tips for public transport, restaurants, grocery stores, etc. We stayed for four nights and of course visited some of the main sights, but I think our favourite was when we strolled through the big park near Sergio's place, down to the Trastevere neighbourhood. We were there on a weekday and there were very few people in the park, and all locals ... a welcome respite from the tourist hordes downtown (of which we were a part, of course). There is a big pond with turtles swimming in it, and I even spotted a fox.
The only thing I had a bit of an issue with were some silverfish (bugs) that shared our bathroom with us ... it's something I'm a bit squeamish about, but that may not bother other guests. Also, the wifi was a bit unreliable, kept cutting in and out. But these were minor issues, overall the place was really great, and excellent value.