Kateryna's was wonderful!
Location is great. There is a subway stop right across the road that will get you to the middle of Vienna in no time or you can go for a lovely walk along the river and be there in less than 30 minutes.
The apartment itself is lovely with a great balcony that catches the sun in the afternoon.
Kateryna was great and filled us in on everything we needed to know for our stay! I would definitely stay here again if I come back to Vienna