The four of us (3 generations of ladies) had a wonderful time staying at this apartment in Castello for 3 nights. It is a little off the beaten path but accessible to everything and in an absolutely charming part of Venice, right near the Chiesa San Francesco della Vigna. Co-host Andrew met us at the water taxi stop, helped us with our luggage, and gave us great tips for the apartment and the neighborhood. Andrew's suggestions for where to eat and where to go (and how to navigate back to the apartment!) were very helpful. The kitchen/dining area is a little small but perfectly fine for our use of it (light breakfast in the morning). We made good use of the washer and drying rack. One bedroom is quite a bit bigger than the other, and we had the beds set up with one double bed + one twin in the bigger room, two twins in the smaller room. The second room was a little tight with the two twins and there would be more space for luggage if set up as a double bed. There isn't a lot of hanging space for clothes, but that wasn't a huge issue for us (there are a dresser and some shelves for clothes). Looking back on it, we probably should have asked for one of the twin beds to be put into the living room, or we should have put the two twins right next to each other to make better use of the space and have a little more room for our suitcases. Air conditioning worked great (and was very necessary in July), and having two bathrooms really was luxurious with the four of us. (Bathrooms are very nice and seem newly renovated.)
Overall the apartment was roomy enough, and my sister-in-law and I appreciated being able to stay up and talk comfortably at night in the living room.
The apartment is close to a water taxi stop, a couple of vaporetto stops, a very nice cafe (cafe Santa Giustina), a good bakery (which also sells light groceries), and a fruit stand. Lots of good restaurants in that sestiere. We loved how quiet and protected from the tourist traffic jam the apartment is; the neighborhood in general is very local but friendly. One day we walked over to Piazza San Marco and the other day we took the vaporetto to see Venice from the water--both were easily accessible. Our only problem with the location was when we ventured across town to hear live music by Interpreti Veneziani at la Chiesa San Vidal near the Accademia bridge, which is a 25 minute walk in daylight. The Vivaldi concert finished around 1030, and walking back across town at night in the rain was an adventure with my mother-in-law, who is very fit but 76 and a little unstable on the wet pavement especially at the canal crossings. The rest of us (including the 11 year old) had no problem. If we knew the vaporetto system well it would have been fine, I think. For us, the charm of the neighborhood more than made up for the slightly longer walking times. I think especially if you are visiting Venice for Biennale, it's a perfect spot.
The most unusual activity we did was the paper marbling class at Arzan Art Studio 3 minutes away. Highly recommended.