Starting with a summary: A great place in an amazing location spoiled by impracticality and a bad host.
This is a fairly large apartment with high ceilings, two sizeable bedrooms, a large living room, 2 1/2 baths and a decent kitchen and dining room space. Even though the building is quite unassuming and old (historic), the apartment seems to have been recently renovated.
It is located in a (literally) historic courtyard, steps away from Stephansplatz and the heart of Vienna, with most of the important attractions just minutes away. The Buxbaum restaurant at the courtyard is a gem.
Despite all of this, the apartment suffers from a severe case of form over function. The choice of furniture for the living room is designed to look cool (considering looks are subjective). The large, modern chairs are quite uncomfortable, and I it is difficult to seat on them for more than a moment. The sofa is just terrible. It is actually not a sofa but rather multiple rectangular pieces arranged to look like a sofa. There is a thin layer of foam placed over hard wood and watching TV on the sofa turned out to be too painful. I had my 12-year-old ask me to just watch a movie on the computer screen in bed as sitting on the "sofa" in front of the TV was just not fun...
The dining area is large, but the cylindrical shaped stools are just as uncomfortable as the sofa and spoil conversations over a meal.
The bedrooms are large, and the beds are quite comfortable, so is the shower area. However, there are no mirrors on the sink, located in the middle of the bedroom. Shaving is done by feel and touch and forget about looking in the mirror to put make up on or brush your teeth.
But this is not what really spoils this place. This honor goes to the host. I have a feeling that "Harry" is just a name used by a group of people that, sometimes, respond to your messages. The level of proficiency in English varies drastically between messages so it is difficult to believe this is actually one person.
Starting with our check-in which was chaotic, to not having internet for a couple of days as the router was out of credits, to the dishwasher not working, every time we tried to contact "Harry" we either got a cryptic response in broken English, a rude response in OK English or, more often than not, no response at all.
We are seasoned travelers and have stayed in AirBnB's all over the Europe and elsewhere. We had our fair share of bad hosts, but this was something else.
So, in summary: A great place in an amazing location spoiled by impracticality and a bad host. If you find another place in the same area with a Superhost, go for it. Otherwise, be ready to deal with "Harry" and the unique features of the apartment.