Host speaks excellent English and Russian, very quick to communicate. The apartment is very close to the subway, and its overall location is excellent - two stations to Wien Mitte (trains to/from the airport and major S-bahn node), 4 stations to Stefanplatz, 15 minutes by foot to Prater park. The neighborhood is lovely and quiet, with lots of small restaurants/cafes, children playgrounds and a couple of supermarkets nearby (if you're into Indian food, you've got to check out Saffron Restaurant on the corner of Keinergasse and Baumgasse, it's amazing).
The apartment itself is spacious and comfortable, with good heating (which is kind of important in early April), decent Internet connection, etc - everything you may need to stay with a small child is there. Our 1.5 years old son enjoyed the baby bed (especially the fact that he can safely get in and out at will - something that the larger bed we have at home doesn't allow), and we found that we don't have to change the routines he's accustomed to that much.
Overall, we highly recommend Jovana's place, especially if you're coming to Vienna with a child.