Hannes apartment is as described in the presentation and pictures.
It might be a bit small for several people, but for us it was perfect - we used it mostly to have a place to sleep, we were around the city the rest of the day.
Careful : the water heater capacity may be a bit low - but we managed to avoid the issue by setting it on the hottest feature, and it was enough.

The place was clean and neat when we arrived - though some of the towels had a smoke smell. Also, the couch may be a bit tricky to open - we didn't see there was a support for the mattress underneath it at first, and the first night was a bit uncomfortable, but that was our mistake only!

We didn't get the chance to meet Hannes, but he has always been very responsive by email or Airbnb, as well as his friend David who took care of us during his absence.
Regarding location, you're only 5 min by foot from the airport express bus, and 10-15 min from the city center (Stephansplatz etc.)
If you're looking for a laid-back, not expensive place to spend great holidays in Vienna, this is the place!