I stayed in the apartment four nights and it was actually better than I expected. The bedroom is bigger than what it looks like on the photos. The apartment is right in the center of Mariahilferstrasse, and high enough so if you look through the window you will see the church. Right next to it is a stop of the Bus 13A and it takes you to straight to Hauptbahnhof, while U3 goes to St. Stephens. I was zipping around the city as my friends and I had our annual pre-Xmas reunion that included events in several places, and I think I used taxi only once in 4 days.
I slept great: with closed windows the street buzz fades away. Apartment is super clean and one thing that I really appreciated was the Nespresso coffee maker with capsules that Thomas generously left in the apartment. Would definitely come again, and for this visit is is ten out of five!