This is a beautiful old flat right in the center of the touristy parts of Paris, between the Garnier opera house and the Louvre. The place isn't exactly huge, but it very comfortably slept 5 of us and with plenty of room to hang out and rest between sightseeing. You can easily walk to most of the most famous attractions, and because of the Metro proximity it's easy to get to anything else (main train stations, airports, etc).
Fréderic is a professional host who really knows what he's doing. There are very detailed instructions for how to check-in and out and even how to use the appliances, so there's absolutely nothing to figure out. It's a bit on the pricey side but I still found it to be a great value for the location, space, and comfort.