The apartment is very good situated for sightseeing. You can easily walk to the "center" of Vienna and the nearby neighbourhood is also really nice with shops, supermarkets and restaurants around the corner.
The communication with Stefan beforehand was quick and easy. On our day of arrival he waited for us and also provided us with a list of what to do in Vienna. Also he provided a baby bed.
Very nice: there was coffee to enjoy in the cupboard!
Negative for us was the cleanliness in the apartment. The cupboards and doors in the ktchen for example were dirty and there was dust on every furniture that hadn't been used in a while. Also the couch hat so many spots that I personally didn't want to sit down neither sleep there. The curtains really need to be washed as well.
Overall we felt that there was missing cosiness and we prefered to stay out long and only come home to sleep.