We stayed at AD Place during a rainy weekend in Venice. It was a lovely hotel, very romantic rooms and we were pleased to have a huge window overlooking the canal below -- we could watch the gondolas pass... or even just the Venetian garbage boats (never have I been so impressed by a garbage truck ;)).
The room was very romantic -- we loved all the furnishings and bedding. Very unique. Everything else I'd say was good, not great. Breakfast was good, but if you came a little late and they were out of something -- they were not refilling it for you. At a hotel of this price, that was a little disappointing. Also, it seems they've opted for style over function in a lot of ways -- very stylish bar upstairs, but unclear if it's staffed or help yourself; very stylish entryway, but sometimes hard to find the front desk person.
All that said, we did like AD Place. The staff was friendly and gave us good recommendations on where to eat and drink, and what to see and do. If this is a huge splurge for you, I'd definitely investigate other options. But if you're intrigued by the decor and looking for a romantic hotel in Venice, this one does the trick.