This building predates us all (late 1800s, I'm told), so is very fitting for a stay in Vienna, especially if you enjoy stepping back in time. The flat is beautifully decorated with examples from Monet and the local Klimt on the walls. The flat is also very spacious, and the kitchen is very well-stocked for cooking.
The location is perfect. A cathedral is in direct view from the front window. It's a quiet area, yet with plenty of great food/cafes/etc. around the corner. It's walkable to the city center and a couple of the major parks, with public transport (strassen-bahn) on the same block.
The host, Barbara, is also lovely and accommodating, while leaving you to yourself during your stay. I'll be staying here again next time I'm in town, without question!