This was a really great place to stay. The apartment is large, light and comfortable, and is in an excellent location: it's a quiet, residential area (although the next road over is the main street in that part of the city, so there are a number of shops nearby), but has tram, U-bahn, S-bahn and bus stops within a few minutes' walk, so you can easily get to anywhere in the city.
Yuda was a very helpful host, contacting me well in advance to provide directions and arrange a check-in time, and was always responsive when I had a question. He wasn't in the city when I arrived, but his cousin and his wife showed me the apartment and explained everything on Yuda's behalf.
I recommend this apartment very highly. It was just right, and very reasonably priced, for a visit to Vienna.