I stayed at the Santa Marina hotel in Venice for three nights beginning 20th October 2012. The hotel is conveniently located and the stay was pleasant enough.
However, this is not a 4 star hotel. The rooms were nice enough, no complaints, the pictures are accurate - but as space comes at a premium, they were a bit pokey and the bathrooms were shower only.They don't provide you with tea/coffee in your rooms (which we would have considered a basic service of even a 3 star hotel), there were no iron facilities within the rooms and when asked whether we could arrange for this, we were told it would have to be ordered the day before - there were no price lists so we had no idea how much this would cost. When we called for further details, the receptionist was evasive. In general the staff are civil but not overly welcoming or friendly. Overall, as we spent the majority of our time out - this was no great shakes, it served its purpose and was part of a decent value deal.

All employees are respectful and very kind. We were welcomed by a receptionist who made a brief account of the main attractions.
Comfortable room with a view and an independent access if you want privacy. The street might get noise at times but it didn't bother that much.
Prices at the bar are reasonable (3 euro a coffee)
When booking ask for a room in the main building, follow my advice.
Good location, in the middle of Rialto and Piazza San Marco.

We recently returned from 2 weeks in Italy. The start of our vacation was Venice and this was our hotel selection. I nearly cried thinking this was going to be how all our hotels in Italy would turn out. To start with, the hotel is not near the boat station and it's very difficult to find, so we were lugging our suitcases through the narrow streets and were lost for about an hour. Then, the people at the front desk were incredibly rude the entire duration of the stay. Last, we got to our hotel room and I literally thought it was a joke or some kind of mistake. We were in "501", which I now see previous people have complained about, but I was of the belief "it won't happen to me..". Well it did and it was terrible. You pay for a normal room and then you get stuck here. The room is right past the kitchen and you hear them clanging plates 24 hours a day. There's not a normal shower and your bedroom window looks out onto the courtyard where guests are eating breakfast, so you can never open the curtains. Further, there must be dust mites or something in the room as I developed severe allergies which made the vacation unpleasant. And the armoire in the room smelled absolutely terrible. I would not recommend this hotel to anyone - terrible value and incredibly disappointing for a 4-star hotel.

We stayed 2 nights in this hotel and although maybe from outside it doesn't look great (perhpas like the majority of buildings in Venice!) the inside is beautiful. The staff were very friendly and proved competent [when we complained of noise of our neighbours (over us) and solved the problem in 2 minutes]. The rooms were very modern and the bathrooms excellent and beds very comfy.
The situation is also a plus being 6 minutes walk from Rialto bridge - if you don't get lost!
Breakfast was fabulous: hot and cold and no shortage.