This was a great place for our first time in Paris! Like other reviewers have pointed out it is very central and in a great neighborhood with good public transportation options within a few blocks. The Marais has a lot of character and with endless cafe and bar options, while still only being a 30 minute walk (and 5 minute metro trip) to the Louvre. Joaquin's apartment is off of a cool side street and in the inner part of the building above a court yard, so for how busy and noisy the street is right outside you can't really hear it at all from the apartment! As most reviewers have also pointed out it is a very simple studio with a small kitchen and a bathroom with a washer-everything you need!
We only met Joaquin once, but he was very helpful and seemed like a genuinely nice person who was there to make sure your stay was a good one. Always appreciated.