Very good location - those of you arriving at Gare du Nord would find it particularly convenient; it is close to two Metro stations. The area is quite buzzing (though the street is quiet enough), with bars and restaurants/cafés a few minutes walk away. There is also a supermarket next door and green grocers nearby.
Although the flat (or apartment in US English!) may seem a little small from the pictures it's actually quite spacious for two people. The oven is small and there's only two cooking hobs, but I doubt that would be an issue for many people and the hobs are high quality electric ones which get hot instantly. The shower is strong and the bed is comfortable.
The large windows are nice for letting in some breeze on a hot day and there are speakers for putting on some choooons while you make breakfast/get changed. We were given use of the coffee machine which we enjoyed using.
Pauline was very helpful and communicative and we had no problems contacting her.