Everything was great. Francesco responds on messages promptly, he met us in the apartment on time, he was nice and polite. The apartment is exactly as described. It is quite small, but it is clean and has everything that you might need. Though the weather was very hot, the apartment was cool. The only disadvantage is that the mobile and internet connection is not very good inside the apartment.
The best thing about the apartment is its location. It is right next to Campo di Fiori, where you can find good places to eat. It is 2 minutes walk from a Piazza Benedetto Cairoli which has good transport interchange and about 10 minutes walk to Piazza Venezia and The Coliseum and about 7 minutes to Pantheon, and it's walking distance to Trastevere. So the location is really great.
So would definitely recommend the apartment, great value.