Vienna, Hannes as a host, and the apartment are three mandatory ones for the best trip in Vienna.
Hannes is very communicative and helped me through the whole trip. I was later checked in so he bought a key safe in order to check-in without any trouble at night. Also, he responded immediately when I had some questions.
The apartment itself is super cozy, clean, and includes all the tools. It's very calm and quiet around the apartment, I could hear only birds whistling. The location is very near to the center and subway. The Starbucks is 5 minutes away, which was a must thing to do in the morning for me.
So don't hesitate just go for it, cheers :)!