The pros with this rental are the location and the pure practicality of the place. Rooms are very clean and spacious enough for two people. Housekeeping is great, and so is the quality of the bed. Another great feature is that you can leave luggage in a couple large lockers after you evacuated your room on the departure day, the code for the front entrance to the building stays the same through the day. You can't lock for your luggage though, these are open, but with very few rooms in use safety feels ok. I wouldn't put my computer, money or passport there though.
All considered, this is probably quite good value for money if you are just in Venice for a couple days, with just a few minutes to walk from buses and trains, siting next to the Grand Canal with sevaral major Vaporetto stops to chose from.
The cons are the noise and the loss of personal contact. Rooms are very basic, and it's more like staying in a regular hotel than a B&B, but without any staff on site. There's no breakfast available, so calling it B&B is a bit of a misnomer. The traffic on the river stay very busy long into the night, so if you like to sleep with the window open you better not be bothered about loud noise coming up from the canal below. I found it somewhat charming, hearing boat engines revving instead of cars.
For a longer stay I would absolutely choose a room in a private home over this, I like to cook my own breakfast and make my own cup of tea. And also to chat with local people. Practical yes, charming no.