Markus' apartment is awesome. It is pretty big (more than comfortable for us , we were two people), it has everything you may need for your stay, and it is in a very nice residential neighbourhood.
The location for the appartment is OK, it is a little away from historic vienna, you can either to take a 20 min bus, use the subway (10 minutes walking + 10 minute subway) or walk (40-50 minutes). It is not a deal breaker at all, and it pays off in the sense that the location of the appartment is very quiet.