The flat was great. It is spacious and uncluttered, with a fresh and clean feel. I loved the light airy living room with the comfy sofa. Everything in the flat seemed high quality and in good condition, including things like the washing machine and the shower.
The flat is really quiet, and in an attractive area. The 37 tram goes past the end of the street, and Spittelau station (U4 & U6) is just around the corner. There is unrestricted street parking outside, and I managed to park there for most of my stay.
Finally, Heidi is lovely.
I would warmly recommend this flat to anyone coming to Vienna.