We really enjoyed our stay in Vienna. This apartment location could not be any closer to city center. Everything is within walking distance including trams and U1, U4 and U3 lines. Great restaurant locations nearby. We really enjoyed our stay. It is a city center location, so you do have city center noises in the evenings/mornings so if you are a very light sleeper, you may want to consider other locations (this is just a factor for all city centers).
Apartment had lots of room and it allowed our kids room to play and strath out.
Greichen was very responsive. Checkin was smooth and easy. A perfect host. We definitely recommend.