This is a flat on the perfect location in Paris. We stayed there for seven weeks for work, and it was walking distance basically everywhere. The wonderful Luxembourg park is five minutes away. You are just in the middle of the great shopping and restaurant area St. German de Prés. It's 12 minutes walk to Louvre and 7 minutes walk to the Seine. So location wise the place is perfect.
The flat does not face to the street, so you are not disturbed by traffic. The advertisement says it is a "loft", but it is a first floor flat. There is no sun coming into the flat, which makes it cool in summertime, but also somewhat dark.
The heating works really well when it is cold outside.
The flat is a little worn down. Everything works well, but furnitures, bathroom and equipment is not fresh. If you can live with that, the place is fine. Be aware that there is a school (kids level) next door. It you spend a lot of time in the flat between 08:30 and 18:00 you will be disturbed by shouting kids some minutes every hour. The backyard is also somewhat noisy from very early morning, since garbage bins are being dragged out and in again basically every morning around 6 and 7.
The flat suits two persons really well. Four persons can be a little crowdy, but not for a few days.