The flat was the best out of seven I ever had in Venice. It is spacious and light-flooded (not a matter of course in Venice) and the interior is elegant.
The location is perfect: A supermarket is opposite of the gate, restaurants (rather expensive) are on the square or two to three minutes away (e.g. Osteria al Portego, one of my favourites in Venice). The fish market is also comfortably to reach.
To one of the centres of nightlife (Campo Erberia) it is a short walk, the other hotspots at Misericordia - Ormesini are fifteen minutes to walk (Paradiso Perduto to recommend), and for Campo Santa Margherita (Margarita in Venetian) with Margaret Duchamp, my favourite bar in Venice, you take the vaporetto line 1 to Ca' Rezzonico.
The main sights are very close: Santa Maria Formosa, San Zanipolo (Santi Giovanni e Paolo), Rialto Bridge and Piazza San Marco (one to ten minutes). To the Biennale you need a vaporetto, but it was not Francescas decision to locate it at the very end of Venice. The railway station and the bus terminal are not centrally located as well, but by vaporetto you are there within ten minutes.
Francesca is the best choice for you!