I stayed at Suzanne's place for a bit more than 2 months and I really enjoyed living there. It is decorated nicely and with all amenities one may need for a short stay. The bed is very comfortable and so is the sofa. The apartment is located in a very nice and elegant part of Madrid and just 3-4 minutes away to different metro stations. It is also very close to Seine, Eiffel Tower, Champs-Élysées, the Arch and many other places.
It is true that it is on the 4th floor without a lift but this flat if it had a lift it would be much more expensive. I'd definitely stay there again when I return to Paris for work.