After a few initial bumps, this was a good base for enjoying Paris. Unfortunately, Amanda's friend who was letting me in was 45 minutes late, without much of an apology or explanation. Also, the elevator was broken when I checked in (though was soon repaired) -- so I needed to carry my suitcase up 140+ stairs. When I opened the sofa bed to make the bed, it was covered with baguette crumbs and had a plastic fork and a packet of tissues lodged in the cracks.
However, overall I really appreciated staying in the studio.
The location is wonderful -- near the RER station that goes straight to Charles de Gaulle Airport, and near many bus lines. Luxembourg Garden is just a few blocks away, and is a delightful place to eat a picnic, people-watch and just relax. There is a great organic grocery store around the corner, and many nice shops in the neighborhood. Amanda provided a helpful list of tips and recommendations.
The studio itself is very small, but gets great light and has a stunning view of the Pantheon. It is cleverly designed to make the best use of the space (about 125 sq ft total). There are lots of cubbyholes and built-in shelves and closets to store things. The kitchen is well stocked, and I enjoyed cooking a few meals there. I really appreciated having a washer/dryer in the unit, and the shower was great.
Do be aware that if you are taller than about 5'6", you will need to be careful to not hit your head in about 1/3 of the unit (the ceiling angles down pretty sharply). The bathroom sink is tiny, and it was hard to brush my teeth or wash my face because the vanity was large and left little clearance above the sink. Also, although the unit has its own bathroom, there is a communal toilet across the hall, and other guests could be noisy going in and out of there at all hours. Because Amanda wanted me to return the key in person during check-out, be aware that this could be a little challenging if you have a very early departure time.