We stayed at Valentina's place for two nights and the flat is at the perfect location for such short city break :)
One of the great things about the location is that it has a city bike station literally behind the corner, so if you register for 1 euro, you can practically use bike for free for the entire stay in Vienna (as long as you return the bike to a station) - it's an awesome way of sightseeing as you still get to be outside and observe the beauty of the city, yet move much faster!