I have stayed at Francesco & Emmanuel's place for three months. It is a really well considered studio, designed with a lot of attention for detail, while also optimizing the available space. The mezzanine didn't bother me, the kitchen really comes in handy for basic cooking. The place made me think of the beautiful tiny living projects you see at 'Never too small' : great solution to maximize living quality in a studio.
The appartement looks out to a small harbor, and from the sofa you can see the reflection in the water. You can jog next to the boats and then continue your run to the Seine. The appartement is well connected with multiple metro, bus and train lines nearby, but you can also just walk to the Marais area, the Seine and the Jardin des Plantes, which are great places to hang out and have a drink. There are a couple of markets in the neighborhood, as well as grocery stores and laundromats. The area also has a few gyms.
Having stayed there for a few months, I was also very happy there is a table where you can work from home. The Internet connection was flawless, and different bars in the neighborhood also allow for great work places if you want to change the scenery.
All together, I recommend both the apartment and the area.