This is a lovely and quiet little apartment in the heart of Paris. It is ideal for getting the most out of the city while having peace and quiet at work. Like most Parisian apartments, it's quite small (especially the bathroom), but sufficient for a single traveler or even a couple. There is great light, and the windows overlook the Prime Minister's serene garden. The bed is very comfortable, and the kitchen table is also quite spacious.
Karin was a great host. She was traveling during my stay, but made all the necessary arrangements and kept in touch whenever I needed anything.
I stayed for a month while researching at the BNF and the Institut de France, and it was great to be within walking distance of pretty much everything in the city. The apartment is also close to 3 metro lines (10, 12, 13).
There were ants on the floor (it was quite hot in the summer), but the spray took care of them easily. It is a 4th floor (5th American) walk-up, so you should be in decent shape if you plan to stay here. Otherwise, it was a great home away from home, and I would definitely stay here next time I'm in the City of Lights!