This place has everything what you need. You are NOT booking for a 5 star hotel. This place is very central (Castello, near Arsenale - and very close to the Biennale). You can walk to the San Marco Square - if you want.
The room is simple, but has AC, a very good mattress, a separate toilet, shower and even a french bidet. And it's very quite.
The breakfast buffet is huge (long :-) ). Very good french baguette bread, yogurt, salami (and more), cheese (and more), cereals, several juices and a machine for tea or coffee.
So - for the price AND for Venice, I'd say it's perfect, if you don't need luxury.