Ulrike's place is a great option for staying in Vienna. She is really nice and helpful, the apartment is clean and nicely decorated, and the room is perfect (it has a small closet, a desk, even a cd player), you will have your own bathroom which is great. The kitchen is well equipped, you'll find everything you need for cooking. There is also a big supermarket a couple of blocks away where you can find anything you need and more.
Ulrike and her son make you feel welcome all the time but are also very respectful of your own privacy.
The building is located not so close to Vienna center but is very well connected, there is a subway station ten minutes walking.
Hope you will enjoy your stay at Ulrike's as I did it.