Stayed here for three nights and only have one complaint.
The location is the best thing about this hotel, you are literally next to San Marco square and on the grand canal. It was so convenient for us as we could pop back to the hotel for a refresh whenever needed.
The room was of an ideal size, and we were located in the annex building around the corner from the main part of the hotel. Staff were helpful and there whenever needed. They booked a water taxi for us to the hotel without hesitating.
The only complaint we had was that the breakfast is truly awful. The worst I've ever experienced and everyone else at the breakfast room was feeling the same. If you stay here I would skip the breakfast and go to a local cafe instead.