Frédéric's place has a lot to recommend it. It's a very nice two-bedroom place on the second floor of a pretty typical Roman townhouse, with an entry from a private alley with a locking door on the street. Everything is nice and straightforward with that. Its location is excellent, being within sight of the Colosseum and Via Cavour, which you can use to reach the rest of Rome. The photos do make it look a little larger than it is, but it's fine.
The apartment is nicely furnished, with the nice kitchen nook that appears to be standard practice in Roman apartments. We had no complaints about that. We were there in April, so we didn't have to deal with either heat or A/C, and we didn't watch any TV, so we can't speak to any of those features. The shower was fine, with no shortage of hot water, though it took a little experimenting to figure out how it worked. (A sign explaining how to use it would be nice.)
Across the street is a restaurant that is sometimes used as a staging area for tour groups, so there was noise on occasion from that, but nothing too bad. There was only one inherent drawback that I could see. The larger of the two bedrooms is next to the street itself, with windows on it, which means that you get a fair amount of street noise there. The tall casement windows do open, which was nice (especially since there's no outdoor space with this place-- no balconies or patios), and close tightly, and you can close the shutters and latch them at night to cut down on light coming in in the morning. The beds were comfortable and the furniture, some of it antique, was charming.
Frederic and his family live just above the flat, but we weren't disturbed by them. The wi-fi was fine most of the time for four of us, but did cut out for a day or so. Frédéric, when we contacted him, said that it was his phone service entirely that was out. He dealt with the phone company until it came back on.