We enjoyed staying in Tino and Emilie's flat. It was comfortable, clean, light and airy and provided all we needed for our stay in Vienna. It was on the first floor of an apartment building, which had both an entry-phone system and a lift.
There was a king-size bed which was reasonably comfortable, a comfy sofa, and table and chairs for eating. No TV - but that was fine with us. A well-equipped kitchen, which supplied everything we needed (except for a corkscrew!). The bathroom had a deep, half-size sit-up bath with shower-head, which was fine for us, but might be difficult to get in and out of if you have mobility problems. There is wi-fi in the flat, but it's not a particularly strong signal, so it can be a bit erratic.
Access to and from Vienna centre was quick and easy, needing just one tram ride and a few minutes walk (the public transport system in Vienna is excellent). There are several restaurants and a great street market nearby for food.
Tino lives nearby, and was very helpful and friendly, and responded quickly to our queries and requests.
Overall, an excellent base for sightseeing around Vienna.