Betti's place is, as the other reviews say, old but quaint, apart from the bathroom which is much newer. The apartment is lovely and warm in cold weather.
The location is excellent (10-15 minutes walk from San Marco square) and right by the Zattere boat stops for the Alilaguna (e.g. to/from airport) and the Vaporetto (multiple destinations) lines.
There were five of us and we found it better to gather together in the kitchen diner than the lounge. The kitchen was perfectly sufficient to enable us to cook breakfast and evening meals when we wanted to. For those who want to food shop for eating in the Conad supermarket (one of Betti's local recommendations) is nearby and very good.
The Osterio Al Squero bar round the corner (first canal to the west) is fantastic - check it out!
Tip - Definitely go to the Peggy Guggenheim Collection (nearby) as the art is amazing. If you go to the Doge's Palace we strongly recommend the "Secret Itineraries Tour" - fascinating.