The flat is amazing: modern, in the best district ever (Trastevere, nice restaurants and dolce vita), in a small private aisle that makes it very quiet. There is good air conditioning (trust me, you do need it).
When we got in the flat, there were already snacks and everything you need for breakfast. During the stay, we only had a small problem with the shower, and Federico ' s staff fixed it immediately (on a Sunday!).
This is definitely the place you need to stay in Rome in the best conditions.