Benjamin is a wonderful, hospitable host. We have not been in a place with so many small, thoughtful touches from home made spa water to leaving a guitar as part decoration, part entertainment.
The flat is small, inevitably for this part of Paris at this value, but it is perfectly designed. The quirky old alley at the entrance and the stairway up to the flat reminded me of descriptions in A Tale of Two Cities! The flat itself is has all the amenities and is really cosy. We spent a lot of time walking around Le Marais, crossing down to the 5th arrondissement and it was always so good to get back.
As for location, you will be hard pressed to find better.