Leo's apartment is lovely! I stayed there with my mother and grandmother and it had everything we needed. It is quiet, spacious, clean and cozy. I also loved the location, very close to 1st district, Naschmarkt and Mariahilfer Strasse (shopping street in 6th district).
It was very convenient for my grandma too, with very few steps to climb and bus stops to above mentioned locations just in front of the building.
Leo is a very helpful host and very fast to respond to any of your questions.
I would gladly stay there again and can recommend it to anyone.