We stayed at the flat for one night. Great location, the room and flat in general were nice and clean. Giovanni and Sara were very welcoming. Giovanni gave us a map with pointers and locations to visit, he was great.
The flat is shared with other guests including toilet and showers. It wasnt a problem for us but it might be a consideration.
Downsides -
There is no A/C, only a fan. This is crucial since the summer in Venice is hot as hell day and night.
The flat is at the 4th floor with 90 steep steps and no elevator.
To sum up it was a good first experience with airbnb and sufficed for one night in venice. Recommended!