We loved our apartment in Venice! Serena was a great host and told us of the two options to get to the apartment. We chose to splurge on a water taxi vs. the water bus, and were able to get within a few minute walk of the apartment. She met us and walked us through everything and was very helpful.
As for the location, it's amazing! It's literally about a 3 minute walk from Piazza San Marco in the heart of Venice. It's about a 10-15 minute walk from the Rialto as well.
The apartment is beautiful, and very modern and tastefully decorated in an old building! We would highly recommend this apartment to our friends visiting Venice!