My wife and I stayed here for two nights in Jan of 2012 as recommend by the Rick Steves Italy travel book.
As this is the off-season, we were able to walk in and book room 20 for just 99 euro per night which included breakfast and wi-fi. To get this Internet price we paid in full at time of booking.
After exploring for two days, we've not seen a hotel better located. It is about a block from St. Mark's Square.
The bed was comfortable, there are many, many lighting options, a safe, and plenty of furniture. There is a mini-bar stocked with drinks (coke e3.00, water e2.50). The bathroom is large and well equipped, and there was a small balcony to sit at where you can see a bit of one of the canals. It is our understanding that these rooms rent for way, way more during the high season. We had a very good experience here.

We stayed here for a 4 night birthday treat for myself in January.
We arrived late after as a strike effected all transport in Italy. However, we arrived by taxi boat to san marco and found the hotel very quickly by foot! The hotel is fairly small and full of character!
Staff were very friendly and even left a birthday tart with card and plates on by birthday!
Breakfast room offered everything you would expect.
The rooms very clean! The beds were a little hard but was still able to sleep comfortably.
Location great for all venices attractions!
Would recommended this hotel!

Our stay at the Dona Palace, Venice was very nice. Situated seconds from San Marco, the Dona Palace was exceptionally good value. Our room was lovely, very comfortable bed, linen and marble bathroom. I noticed excellent facilities if one was in anyway disabled - lifts, access routes, bathrooms etc. The breakfast had a very good selection. Staff was superb from reception (Farid), to bellboys and waitresses. They made the stay very pleasant. In particular, Farid found us a fantastic restaurant, 2 minutes away and made reservations for us.Charning helpful and funny. Taxi access from private hotel landing made a big difference when exiting the hotel with bags to the airport.

It is very well located for a Venice holiday as it is close to St Mark's Square and its "waterbus" terminal. The reception staff were friendly and always there. The size of our Double room was exactly what we needed. It was warm and clean with a good en-suite shower room. Breakfast was a wide range of foods and more great coffee than I could drink.