Casa Giardini is a great place to visit and stay in Venice. It's situated in a strategic position very close to Piazza San Marco (around 15 min by foot) and 5 minutes to the Arsenale vaporetto boat bus stop, so you can reach the city center, Murano/Burano and the train station really easily.
Simonetta has been very kind, she suggested us some good place to eat and met our needs, e.g. in our last day in Venice she let us leave our luggage in the b&b.
Casa Giardini has definitely a really good value for its cost.