Live like a Parisian!
We truly enjoyed our stay - the location of the apartment could not be better. You have the bastille in front of you, and the you just walk 3 minutes and your're in Le Marais. The number of Bars and Restaurants just in the neighborhood was astounding. We had excellent food from any number of cuisines. The Subway (1,5,8) is steps away and is probably one of the most efficient subway systems that I have experienced.
It can be a bit loud, especially towards the weekends, but the windows are fairly solid and well insulated so that the noise is kept under control.
For us, a special treat was the kitchen, because it allowed us to do local shopping and then cook at home - just like Parisians would do.
For a family of 4 it was ok, especially if you have smaller children - but I think you couldn't go beyond that and I wouldn't recommend it. The showed lacked a shower curtain but this seemed like something by design.
You can leave your luggage in the restaurant downstairs and that works really well, we ended up having a drink there too because they make excellent martinis.
All good - can only reommend.