Flat was as advertised and looks like the pictures. Very clean and comfortable. Communication was excellent before and during the transaction. The only (very minor) downside is that the kitchen corner is a bit small. It didn't bother us at all. But if you expect to do a lot of cooking for a large group of people, it may be worrisome a bit.

Now for the real selling point:
The location of this flat was simply much better than expected. We booked in a hurry and didn't know much about Vienna. It turns out that this area is perfect for a few days. It is near many trams and a metro line, the transit time to anywhere is good. One side is "touristy" and the other direction is full of small bars, restaurants and coffee shops. We were very excited to see that this was also a very walkable distance from the main areas of the city.

The icing on the cake: it is 1 block away from a Christmas Market (at Rathaus, started on the last day of our visit). We got to see the lighting of the Xmas tree many of the other outdoor activities. Good times.