I stayed in Heidi's apartment for approximately 11 months from March 2016-February 2017 and it was a great place to stay in Vienna. The apartment is clean and has all the comforts that you need for a long stay (cookware, cleaning supplies, towels, etc..). Heidi always responds quickly to any questions or concerns and makes sure things stay in proper working order. It looks just like the pictures and is very charming.
The apartment is also a really great location. Even though it is not right in the center of Vienna it is on the U4 and the U6 ubahn lines and the 37/38 street car lines-- this means it is possible to get almost anywhere in Vienna quickly. It was actually more convenient than some apartments located closer to the center, which had less convenient public transit options.
Döbling, the neighborhood, is beautiful and mostly upscale and residential. There is a grocery store 2 minutes walking distance away, and several good cafes and restaurants nearby. In the warm weather it is a great location for visiting the heuriger, for going to the city hiking paths on the outskirts of the city, or for going to one of the public pools. One of Vienna's larger parks, Turkenschanzpark, is nearby and a great place to run, walk, or read.
I loved living here and highly recommend it to anyone looking for a nice place to stay in Vienna.