I LOVED staying in Gerd's flat! It has everything you need to enjoy your time in Vienna. The kitchen was stocked, there was a living room with couch and a TV, and the bedroom had a large, comfortable mattress on which to sleep.
Lots of natural light is available through the windows as well. There are shades that can be drawn if you like it darker.
Note that this place is large enough for 3 or 4 people but the shower is located in the kitchen/dining room so there isn't a lot of privacy in that regard. Hardly a deal breaker and traveling couples shouldn't be phased by it anyway.