I stayed here for about 6 weeks and it was comfortable and good value for a long term stay.
Location:
It is a great location to explore Vienna from. It is <5 min walk to both the U-Bahn or to trams which lead directly to the inner city (District 1) or other areas of interest. It is also just around the corner from the Volksoper. There is a very small Billa a few steps away from the apartment entrance. Larger grocery stores with more variety are within 10 min if walking. It is also right next to Café Weimar, a relaxing and well-decorated Kaffeehaus and WUK, a bar and music venue.
Bathroom/Kitchen
The kitchen/bathroom set up is a little awkward. The shower is directly in the kitchen/anteroom, and although the glass is clouded, can feel a bit uncomfortable. The toilet is in a separate small room. You can definitely hear people and see their shadows if they are in the adjacent hall. This hall isn't too heavily-trafficked, although it is necessary to pass to get to the trash and recycling bins in the courtyard.
My only other complaint would be that the kitchen is a bit cramped. To plug the microwave in, the cord must reach across the stove top. There is very little working room if you plan on cooking a lot. There are basic cooking utensils provided in the cabinets.
Comfort:
I was in Vienna for some very hot days in August and the apartment did not get hot at all! I did not require the fan that was provided.
Host:
Gregor was a very responsive and responsible host. He even came by to address a clogged shower drain.