The apartment is really well situated in the Marais, which is a very chic area. and it's easy to get to the Metro. We used les Filles du Calvaire station; a 5 minute walk (get a book of 10 metro tickets). However also easy to walk all around the locality. Lots of local cafes & bistros. There's a market, small supermarket, bakery, patisserie all within a couple of minutes, around the corner. The apartment is really quite large for central Paris, and decoration and ambience are great. The photographs don't really do it justice. It's on the second floor. we came in Autumn and some of the group feel the cold. The heating is excellent, so no problems there. The whole complex is very secure: a code to get into the front courtyard, a second to enter the building and then your front door lock. Despite being pretty central it is nice and quiet. Koro met us and showed us around, explaining everything thoroughly.
It was a great base for exploring Paris, and a nice peaceful space to return to at the end of the day. I'd definitely book here again.