Excellent place and an excellent, helpful, and responsive host. Nothing is really isolated in Venice, which is ultimately a pedestrian city. The Jazz House is located in a quiet, residential area in Dorsoduro, well away from the tourist throngs, but well positioned for access to food, cafes, etc. Some great restaurants and bars are located only a short walk away (ca. 7-10 minutes), and with twice that effort you can be standing at the Ponte dell'Accademia. Walking in Venice is both a necessity and a treat, so it was never a source of complaint for us, although I can see how it might be challenging for visitors with mobility restrictions.
The apartment is great and well-appointed. We found it a bit cold at first (we visited in November), but Elena soon took steps to improve the situation. Overall, highly recommended.