We had a lovely time staying in Catherine's studio. It's well located in the Marais district and near several metro stations (Temple is probably closest). The studio itself is seriously tiny, but it is clean and has everything you need for a city trip, and it even has a television. The shower is also pretty good. Catherine was easily reachable and offered very flexible check-in and check-out times. We would definitely stay here again!
One possible improvement: there are several small and very handy shelves in the bathroom and the main room. However, they need to be screwed in a little tighter, because it is impossible to put anything on them now.