We just have stayed for 5 nights at the Palazzo Zen, which in my opinion is more of a huge camping in Venetian style. So please do not get too much excited about the word Palace!
The location is perfect, easy to come from the airport, easy to get around the city or to go to other islands.
The host is nice, though not speaking English. With bits of French and Italian, we got to understand each other.
The wish of every person who stayed at his place is that he would do some repair works and care more of the comfort of the guests: install wifi, put new mats on the beds (the double bed would be very welcome!) and get rid of the mess in the cupboards (shelfs are busy with blankets and other stuff in disorder).
Just one thing to add- we did enjoy our stay and even this very old Venetian apartment!