We stayed at the apartment for 10 nights, It was a very good stay. The apartment is very close to metro station (2-3 mins walk), we could travel all over the city from there. It is also very close to a great Japanese restaurant (Donburi - we ate there several times, very recommended), a small bakery and small market. The "Prater" is about 5 minutes walk from the Apartment.
The apartment is well heated, the radiators working very well, we didn't feel the cold weather of Vienna from this apartment. We had very hot water for the whole stay, the shower is great and the water pressure is awesome. The washing machine is working very well, cleaning the clothes without any bad smells.
The apartment has all what a person could need (includes excellent wifi). The communication with the host was excellent.
Very recommended apartment :)