Stefan's place is beautifully decorated, sparkling clean, spacious, and has all the amenities you'd need for a comfy stay -- all of this for a pretty good value compared to many bnb's we've stayed in.
Importantly, I would say that the location takes about 30 mins to walk to the downtown areas that a lot of tourists would be interested in. However, it is only 5 minutes or so from the underground (with great breakfast stops along the way such as the Budapest Bistro). The underground access is really great for getting anywhere in the city -- it takes you right downtown for 2.40 euros per person (with day passes available at a higher rate, but is probably worth it to save your feet some rest while touring through the city). You can go to the Schönbrunn Palace, the Museum Quartier, and many other great spots with relatively little ease.
I'm also a big fan of the check-in process. Just get a code and let yourself in! So easy! A lot of places make you meet folks places and what not -- which is just a hassle. Here, you just arrive and put your things away before heading out on the town.
One last thing, the bed was a bit firm (and the couch and other surfaces were as well). If you like a firm bed, these are great. I slept like a baby and normally I like a soft bed. That said, my partner likes a firm bed and he found that this was a little stiff for his liking.
We also liked the kitchen and espresso-style coffee maker. You have everything you need to cook a nice meal which will save you money relative to a hotel. However, we found that we ate out anyways because we wanted to get a taste of the city, so this didn't really benefit us. Though it is nice to come home after a long day and have some wine or bubbly on the couch while watching Netflix -- which wouldn't be the same in a hotel.
Without a hesitation we will stay here again when we come back to Vienna!