I agree with the prior reviews regarding the location and the space. It is a quick walk to many shops, restaurants and sites. It is also close to a subway stop. The apartment is large with many windows and a usable kitchen plus a washing machine. They even included a drying rack. But there are discrepancies between the online listing and the actual reality of staying there. Little things like no washing machine detergent, the WiFi network and password are different but also more significant things like no one to meet you at 6:00pm because that is too late so I had to pick up the keys from the restaurant next door and many hours before the host responded to requests for washing machine detergent and fans.
We were there during a heat wave and I understood the apartment had no A/C but it also had no fans. With temperatures close to 100 degrees that was a big problem. Eventually two used fans were dropped off but one stopped working after a few hours.
We loved Vienna and liked the apartment but we were very close to moving to an air-conditioned hotel. It was extremely uncomfortable being so hot and trying to sleep.