Christine's apartment is a great option for 1 - 2 travelers visiting Paris. The neighborhood is very local (not buzzing with tourists) and staying, you quickly start to feel like you live in the city, not just visiting. There's a bus that will take you straight to the Marais, a small metro station, a bigger metro station not too much further from there, and is pretty close to Gare du Nord (where Eurostar terminates). But the star is definitely the apartment.
Top floor with many windows to let in the light and sounds of the city, beautiful paint scheme throughout, gorgeous wood beams. It's very thoughtful and tasteful, not cold like so many Airbnb's. You'll definitely love this apartment, despite the 5-floor walk-up.
Would come back again in a heartbeat.