Catherine's apartment is really the perfect place to stay in Paris--right in the heart of everything but still very quiet at night; beautifully decorated with the quite-impressive clay figures made by the owner as well as tasteful African-themed art; comfortable and warm without being overwhelming in any way.
This neighborhood of St. Germain de Pres is fantastically fun, with a zillion restaurants and shops, jazz musicians at the corner in the evening, bakeries to your heart's content, and many gorgeous sights within walking distance. And yet even on the weekends, the apartment remains serene, with few sounds coming up through the closed windows (the weather was cold and rainy so we did not open them once). The kitchen is well-equipped for any range of cooking, including a dishwasher, which we appreciated because we ate breakfast at home most days to try to economize, running downstairs for baguettes in the mornings and making our own espresso in her wonderful pot. But of course there is also a stunning array of restaurants and cafes right outside the door, and despite the weather, the outside heaters above the tables meant we could have as much fresh air (and authentic Parisian cafe experience) as we wanted.
One caveat, only relevant for those with physical challenges: The stairs are a bit of a bear with a heavy suitcase or after a big day of walking--two long winding (though shallow) flights up--but this is literally the only thing we found wanting in the whole place, and we knew from the start they were part of the deal.
We found Catherine to be responsive to any little question, and we REALLY appreciated her good nature when her own plans fell through for the time of our reservation, and rather than cancelling, she couch-surfed to accommodate our stay.
All in all, a lovely Paris visit, made infinitely more so by our stay at Catherine's beautiful home.