We had a good time in Vienna.
I attended a conference at the Messe and my wife explored Vienna.
Everything is in easy walking distance and if the next U bahn and S bahn stop is only 5 minutes away, with direct connection to the airport.
The apartment is perfect for a stay in Vienna, clean, well equipped, quiet with lots of light and fresh air.
Communication with our host was fast and efficient.
In short - highly recommended