I've stayed 6 days in Cathenina's apartment.
It's extremely well located in the heart of St Germain despres, close to markets, good restaurants and fancy stores, some blocks of Paris hot spots.
The place is small, but very well equipped and cozy. It has a comfortable sofa-bed.
To know, like most of places in Paris there's no elevator and it is on the 2-3rd floor.
Main positive Things for me: the place is clean, and Catherina was a outstanding host, always available and trustful.