My partner and I stayed at Bruno's studio in Le Marais for nearly a week in June 2017. The studio is about a 4-minute walk from the Bastille stop, which is on a couple metro lines that connect to many high-demand locations. The studio is refreshingly clean and well lit (it even has A/C!), and is equipped with a full kitchen, which could facilitate a longer stay for some guests.
Bruno was wonderfully communicative with us ahead of our arrival, and checked in mid-week to see how our visit was progressing. He's a genuine hospitality professional who pays careful attention to the information and amenities Paris travelers need.