In a word, the apartment was great.
First of all - location! Prati is my favorite district in Rome, but of course there are better and worse places. It's definitely better! Close to the Vatican, close to Via Cola di Rienzo, close to a well-stocked supermarket, a pharmacy just around the corner, many bars and several restaurants. If anyone would like to use public transport - metro, buses and trams are nearby. In addition, the apartment is located in a very well-kept building with a very neat and nice garden. As it is in the middle of the building, it is also very quiet and the view from every window is nice and very relaxing.
Second - the apartment is large, very nicely designed in one style. For Roman conditions, it is also very bright, especially the bedroom. I think it will also be perfect for summer - it holds the cold very well (maybe even too much :) ). It is also well equipped - like someone were about to live there (I even found a knife to cut fruits). Besides, there is really a lot of space to store clothes. The bed and the sofa are very comfortable.
Third, Riccardo is a very professional host - he welcomed us, explained everything, answered questions quickly and efficiently on all questions during our stay. However, we had a problem with the air conditioning in the bedroom - water spilled onto the floor. Riccardo wrote to us that he would send someone to repair, but during our stay it did not happen (and it was rather not a misunderstanding, because the messages were written in Italian). As it was still a bit cold in the apartment, it would be very nice to have a working air condition - so that the temperature would be at least a little higher in this way.
Finally, I would like to mention one inconvenience - the boiler does not provide so much hot water. If one would like to take a bath or a longer shower, the other person has to wait a while before using the bathroom - otherwise only cold water remains.