One of the best options in Vienna. Located in Meidling, somewhat outside the city centre, but in a nice neighborhood and easy to reach by subway (U6 to "Niederhofstrasse"). Not a hotel (although it can be booked for single nights, too), but check-in is easy. The apartments have little kitchen (fridge, microwave, sink) - and every thing is spotless clean!
Stayed at the Wilma's Apartments in Meidling/Vienna severals times this year 2020, before and during Covid-19.
It really is a good choice for a stay in Vienna, either for private or long-term business trips.
The apartment building is very new, very well organized (kind of automatic check in, no in-house reception, but you can always call 24/7), including washing machine. The rooms are very modern, very (very!) clean and - as far as I know - all have a kitchen with a few dishes, refrigerator, again everything meticiously clean!
If you go outside, you are in Meidling, a really nice, mixed area, from old Vienna bars to traditional cafes, Turkish shops and - at Meidlinger Markt, just around the corner - also some very nice, non-expensive and slightly hip cafes, small restaurants. It is save and still normal. With the U6 you will be at the city center (Westbahnhof) in just a few minutes - and Vienna public transport is really good (every 3 to 5 minutes even late in the evening).
So, really to recommend. Just keep in mind that it is not in downton per se (might be a setback for business trips) and you don't have a traditional hotel with reception, bar etc.