Cannot recommend this place enough! We had a great time at Christine's place.
The location is perfect - right in the Marais, a short walk from the nearest metro station. Plenty of really great places to eat right on the street. Don't be alarmed if you are looking at the street on Google Maps and are worried about noise - the street is busy, but the flat itself is really quiet - we couldn't hear any noise from the street at all.
Christine's place was thoughtful, clean, and very spacious. A binder in the flat included all the instructions we needed to use all the appliances (in multiple languages) and some fantastic recommendations on local places we really enjoyed.
Christine was also extremely communicative the whole time and proactive about identifying any potential issues (we didn't have any problems).