The apartment is in a great central Paris location about 15 mins walk from Gare du Nord and the Seine, with metro access close by.
It was very clean and comfortable with everything you could need for your stay. We were staying for a weekend as a group of 4 adults and it was quite cosy for space. We didn't mind as we were only there for the weekend but if you were staying for longer I'd say it's better suited for 2 people.
The host was very easy to contact prior to arrival and helpful with my questions and accessing the apartment on the day was simple.
The only negative of our stay was there was a lot of noise on the street outside late at night; people shouting and arguing particularly on the corner of Rue Saint-Denis where groups of women seemed to hang around most of the night. I know this can't be controlled by the host as it was outside the apartment but it did wake us repeatedly in the early hours so if you are a light sleeper maybe pack ear plugs.