This apartment is in an amazing location. Under 10 minutes walk to the inner ring (and the tram system), about 6 minutes to the nearest metro station, Karlsplatz, and 3 minutes from the famous Naschmarkt. There are a few supermarkets within 5 minutes walk, and loads of restaurants and cafes nearby.
We walked to Stefansplatz (the very centre of the city) a couple of times, and it was a 20 minute walk at a relaxed tourist pace.
The apartment was clean, spacious and appointed well. The kitchen is small, but we found it perfect for organising breakfasts. There's a Tassimo coffee machine, which is handy.
The hosts were very professional - they clearly understand the needs of people coming to Vienna for a city break or a longer work stay, and the apartment was fitted out thoughtfully. Communication was great - they gave us some excellent tips about local cafes , restaurants, transport, airport transit and even where to get the most accurate weather forecast!
I can highly recommend this apartment. If you're thinking of staying centrally, you're probably better off in this area rather than within the inner ring, as charming local cafes and restaurants are more useful to most city break tourists than Rolex shops and Chanel boutiques.