We stayed at Fero's place for 4 nights - apartment is large, clean and has everything you need during a stay. It is located in pedestrian street with loads of market stands but is very quiet which was interesting to us (you expect a noisy market but there is no noise in the morning or during the day) . Fero (and Paula) gave us good information for check-in and everything went smoothly. A great plus is a garage which is nearby (we came by car so having a place to park was very important to us).
Public transport (S-bahn and metro) stations are within 3 minutes walk. Only downside is that you have to change at least one metro line to get to the points of interest (Stephan's platz, Schonbrunn, etc.
All in all - great experience.