Its an amazing flat with a perfect location!
I attended a concert at the Opera,and being closed was the most important; besides I walked everywhere also to Schönbrunn so you can walk to the most important places in Vienna.
The flat is wonderful really! It has everything that you could need and more (Nespresso pods,tea, sugar, salt and pepper, etc.)
The WIFI is wonderful, the TV has Netflix (I love that, every single aparment and hotel must have Netflix nowadays)
You have a Spar Gourmet (minimarket) 2 blocks away, an ATM in front of the Sacher Cafè (in the corner)
You have restaurants in the area but I love one that is very close to St Stephen's Cathedral: Reinthaler's Beils! The have amazing austrian food and the prices are wonderful.
I highly recommend this flat to everyone who wants to be in the best part of Vienna.
Stefan is an amazing host, always answering my questions, very polite.