The place is very nice, although quite small but big enough for two people. It's fairly close to Mariahilfer strasse (walking distance) and has very good connections to everywhere. The metro station is right across the street.
Borislav is a very good host, really nice and ready to help with any questions you might have. The apartment has everything you might need - coffee and tea, TV, lots of cosmetic products in the bathroom, even some biscuits and apples in the kitchen.
One warning for light sleepers: it tends to get quite noisy at night, which is obviously not the host's fault but it is a thing to consider when choosing a place to stay.
Overall, we had a pleasant stay and we would recommend Borislav's place.