The other reviews for this place are not exaggerated. We stayed at Karen and Raffaele's place for a week and found it to be even more cozy and wonderful than the pictures suggested.
Karen and Raffaele met us at the flat for check-in, made sure we were comfortable, and gave us their famous map of Florence with their favorite restaurants, bars, shops, etc. We came with our own list of recommended places to eat, but ended up using Karen and Raffaele's suggestions the most! When we had trouble getting into the front door, they responded immediately with tips on how to turn the key just right.
The flat is pretty centrally located but on a quiet street. Most everything was a short walk away.
Finally, the terrace is as awesome as you think. We loved starting and ending our days on it, and you will too.
We really enjoyed our stay and hope to be back soon!