in terms of location - Fred's place is as good as it gets. Le Marais for me at least is Paris, and in Le Marais the place is well located. very central yet quiet. the apartment itself is well maintained and equipped. everything was great. Fred was always accommodating and available all the time , even while out of town.
one thing to keep in mind, the top floor may be challenging for 1.87m like myself. but kids loved it so, I'm not that important hehehe.
would definitely be back.