Me and my girlfriend stayed at Olivier's place for a month. Olivier is a great host and made sure we were very comfortable during our stay, with a flexible check in and out process.
The apartment is located in the centre of Le Marais neighborhood over looking a court yard, and with a bakery just down stairs. Being in the centre of Le Marais you obviously everything you need right on your door step. Although it is so central the apartment / building is very quiet and peaceful.
The apartment it self has been renovated and is very clean. It is also very spacious for central Paris.
It has everything you need for a long or short stay, and I would recommend anyone to stay at Olivier's place.