We are a family from Manhattan that was traveling with our mother-in-law that visited during June 2019. This apartment has a great location. Inside the loop, near a bike rental spot, park at end of the street, and restaurants on the block. You are a 5-10 minute walk from the main area of restaurants and sights. Also, the streetcar stops are literally right here. Nice quiet street that allows sleeping with the windows open. Note, there is no air conditioning, which is very common in Austria. 20-foot ceilings and great windows made this a non-issue.
The apartment is spacious and seems bigger than it actually is - given the great layout. No one in our group felt "on top of one another" and the bedrooms have optimal spacing from each other. Kitchen is capable of meals and can accommodate full family sit-down dinners. Note, there are two grocery stores on the block. So, buying food is quite easy. Beautiful building and it was very quiet. Easy in and out. Check in was fine. We had a full week here, so there was little interaction with Christoph's people. But, overall, friendly folks.
We are tough critics and were very happy with the apartment and location. Vienna is amazing. Enjoy.