The apartment is very easy to get to. We came in by car, dropped our luggage and then returned it in the airport and used public transportation to get back and get around town. The airport is no more than 30 minutes away. You can get from the apartment to anywhere worth mentioning in Vienna in about 45 minutes by public transport (including walks and changes), so it was easy to get around despite not being at the very center.
The same building hosts a nice restaurant that does take-away and serves food and drinks until late, which is important for travelers, especially since most of Austria (like most of Europe) closes down at 6PM. There are several supermarkets within easy walking distance and one of the main Tram lines - No. 2, is only 250 meters away and comes every few minutes.
The apartment itself is quiet, modern, spacious, super clean, well equipped with everything, and easy to find. The building also - lobby, elevator, etc. are all sparkling clean and it great shape. The apartment t has a nice decked balcony if you wish to enjoy the air or even work on your tan. Electrical outlets in ample number and wherever you need them - all you need really.
Tina was quick to answer any questions we had. The apartment had all the little things like coffee, salt, oil etc, and a nice bottle of wine and some chocolates in the fridge. The keys are in a coded box and there are two sets so you can split if you need to (we didn't), and are easy to carry around (none of that pound-heavy prison-style large key holder you sometimes get). The place look and feel even better than the pictures convey. We enjoyed staying and would love to come back.