We have been spending 3 nights in Venice in 6 ( parents and 4 children).
The flat is centrally located, very close to San Marco and to the vaporetto ( which is certainly a plus when traveling with children).
The flat has everything needed.
Renting a flat in a Calle is positive as the real Venetian life can be lived, but it has also some drawbacks.
The flat so indeed quite noisy and a bit dark and moldy.
Our stay has been pleasant, however if we would go back to Venice we will probably look for something different ( further from the center and somehow more bright).