Marco's apartment is a truly excellent location for a visit to Venice. As others have already said, the location is just about perfect. It's a two minute walk to the water bus/airport boat stop. Piazza San Marco is a short and pleasant walk. At the same time, though, the neighbourhood is quiet and residential. No enormous crowds coming by, although there is a nice level of activity round about, particularly the interesting boats passing by below the sitting room and kitchen windows.
The apartment itself is well decorated, in good condition, well equipped and comfortable.
During our stay in Venice, my traveling companion and I often commented on how lucky we felt to have chosen Marco's place. We hope to be back sometime in the future.