I enjoyed my stay at Walter's place very much. It is incredibly well situated near main public transportation and only a 25 min walk from the museum quarter. There is also shopping right down the road - everything from groceries to household supplies to clothes.
In the apartment, bedding was clean and it is a nice, wide, open space. Very basic, but priced appropriately. Walter was incredibly patient on my arrival where I was very late and was so welcoming in telling me a bit about Vienna and pointing out places to see on the map. He spent quite a bit of time walking through things.
Just a couple of things to note - the apartment is on the third level so stairs to manage. Also, the kitchen really is very basic - though Walter was wonderful in getting me knives for prepping, and I'm sure would have tried to equip with other things if I'd asked.