We had problems during the check-in. Though the apartment profile clearly states the check in time as "Check In: 12PM (noon) - 7PM", there's 14:00 time on the door plate, and definitely no one's expecting guests before that time. You can drop your luggage, but if you want to get some sleep - you have to wait until the apartment is cleaned, and this time is rather unpredictable. In our case we had to wander around until 15:30, which wasn't a nice walk after a sleepless flight.
We were also charged by 28 euros in cash - Luca called that a "city tax" or "tourist tax". Can't say if that's ok, I just asked Airbnb support about it. Right now there's a tax description in the "House Rules" section of the profile, but I can't say if it was there before, I think I'd notice that. Anyway, I don't understand why it should be charged in cash.
The apartment itself is fine and generally is as described, has good bed and pillows, towels are included. But there are a lot of bird nests just outside the window, and the hungry baby birds start screaming loud as hell since 6:00, making it impossible to sleep with the window open, and it's too hot to sleep with the window closed - make your choise, or get the ear plugs. The overall hearability in the building is also very poor, so it's not very quite place, despite none of the windows are facing some loud street.
There are two supermarkets within minutes of walking, one is even 24H open, but the assortment is surprisingly poor in both. To buy some good food, either Italian or not, consider visiting some supermarket outside the touristic center. The area is swarming with restaurants, though, so it only matters if you plan to cook yourself or get something back home.