We communicated with Marzia over e-mail specially a day before to arrange key. Amazingly Marzia was very responsive. She met us in time to our predetermined location in train station. She accompanied us with water taxi and got us to the stop before her friend took us to the apartment. This was really great. We stayed there only for a night and unfortunately there was no place to hold our luggage (4 bags) and we had to store these in train station both time before check in and after check out. This cost us $75 extra for a night stay. I didn't know this before we booked the apartment.
Apartment was clean but bathroom/shower was too small with hardly any water pressure in shower. Also this apartment was on 3rd floor without elevator so we had to drag our stuff through narrow stair cases which were stacked with people's storage outside their door way so we had to move them to transport our luggage. Marzia's friend was polite and helpful and helped us moving our suitcases.
Our night stay was noisy. Not sure if it was coming from nearby apartments or down from the square but this noise was continuous until morning like 5am. But if you can deal with these, this apartment location is very good. Really close to Realto bridge or very near to water bus stop.