Jean-Michel's studio is a great little nook to serve as home base as you explore Paris. It's tiny but functional and the kitchen has everything you need for basic cooking, which is a huge money saver. Access to a washer/dryer meant I could bring a carry-on suitcase which ensured my luggage wasn't lost and made it easy to use public transit from the airport.
The studio is very central, a quick walk to the Louvre, le quartier Latin, le marché Bastille, and of course, all of le Marais. I stayed there by myself and felt safe in the building and the neighbourhood. I wouldn't want to share it with another person, but if you don't mind being extremely cozy it could work for a couple.
Being on the 3rd floor (by North American standards) in a 7-storey building with a window facing the inner courtyard means the studio isn't filled with lots of daylight. But the benefits outweighed this...only a couple of flights of stairs and it was dead quiet, even when the lively bar scene in the area was in full swing on a Saturday night. Besides, why would you go to Paris to hang out in an apartment? There is so much to see and do, I wasn't in the studio for much more than breakfast, supper and sleeping. It suited my needs perfectly.
The only thing I minded was air quality. With windows closed, it was a little bit stuffy, but with the windows open, I got the occasional cigarette smoke wafting in. My nose is particularly sensitive so I was frequently alternating between open and closed windows. That said, I think this is an unavoidable problem anywhere in Paris because it's a city of heavy smokers, you have to be prepared for that reality. So that would not stop me from renting Jean-Michel's studio again.
Jean-Michel was away during my stay, but he was very prompt to respond to all my questions in advance and provided lots of helpful information about the apartment/building, the neighbourhood, and directions via public transit from the airport. He is an excellent host, very professional.