Very clean, great location, excellent hosts! I highly recommend for a weekend get-away in Vienna.
I was late arriving in Vienna, which I felt terrible about, and my hosts couldn't have been nicer when I eventually arrived at the apartment. They didn't make me feel like I had at all put them out. The location is walkable to Schottentor station (5-10min depending on your speed). From there you can walk the inner ring, then out one street to Karlsplatz (the the U2 line is under), and back to the apartment, catching many of the other major buildings. I felt safe in the neighbourhood, and there was a great coffee shop on the corner.
The apartment was very, very clean, and I had an excellent 2 nights sleep.
Thanks for everything!