I struggle to write an objective review, because there was one big thing that colored my experience: the apartment is literally right above a tram stop and at a busy intersection. This means that I could hear the tram (including announcements) every 3-5 minutes indefinitely between 5AM and 11PM, plus constant traffic. It was more subtle (though still noticable) when the windows were closed, but with the windows open (as is necessary in summer, otherwise the apartment is boiling hot) it was so loud I needed to use noise-cancelling earphones plus earplugs at night to be able to sleep.
The apartment itself was fine, with plenty of space and very basic amenities. The location in the city was nicely accessible to supermarkets, restaurants, and to tram and Ubahn stops. It is approximately 30-45 min walk to the Old Town. Roxana had clear communication about how to check in and check out, and the apartment was very clean. If you will be in Vienna a short time and are not sensitive to noise, it is a good and reliable solution, especially in colder months. Personally I found it overpriced for what was offered, but it might be just right for you.