We were staying in Ali's place as a couple for 3 nights. Communication with Ali was fine, and the place is perfect: Far from crowded places in a lovely neighbourhood but within walking distance to all (biennale) places and sights, vaporetti, supermarkets etc.
As for the AirBnb itself: It is a budget place, which means the beds are saggy, parts of the furniture and equipment are old and a bit rickety (except for the Wifi, which worked excellent and fast). The smell of the bathroom is super bad, I wouldn't want to breathe inside. Ali told us it is because of the canals and would be the same in all Venice houses.