We needed a place with two bedrooms to stay overnight close to the Vienna city center, and this was a great fit.
Pros:
-roomy apartment with two large bedrooms, and additional sofa in the main room. More than enough space for 4 person.
-convenient location close to the city center, tram and U-bahn stops, one minute walk to a food store.
-friendly owner, responsible with very low latency on the email and by the phone, open to discuss schedule adjustments.
Things one may want to be warned about:
-the apartment is one the ground floor, and all the windows are non-transparent mate ones. That was none of a problem for us as we only stayed there overnight.
-the windows are facing a quiet street, but the aparment is close to an intersection with a larger one that has tram movement. You can hear some noice from there with windows open, with windows closed it's pretty quiet however.
We were quite happy with our apartment choice overall.