This is a unique place, an artist's flat in the middle of the most Parisian of Paris' neighborhoods, St Germain. The location is superb, with access to basically everything worth seeing in Paris. The apartment is unique in itself, so personal and intense on one hand, and bohemian at the same time.
You must keep in mind that it is an old building though, with all that this means, like no elevator, smaller spaces and a bit of weird arrangements of the space. You will have to make a few comfort concessions to enjoy what this place has to offer, which is a unique Parisian experience.