I would recommend Yves' apartment without qualification.
Compared to so many of the tiny little bedsits available in Paris, Yves' is spacious, comfortable and extremely well appointed. Everything you could want or need for a few short days in Paris is here, and the location is just perfect. Walking distance from a host of good bars and restaurants, and you can see the canal from your window: perfect for lazy morning walks or evening buffets surrounded by Parisians enjoying the last of the sun together.
Yves was quick and amenable throughout our conversations ahead of time, and his neighbour Jeanne was also incredibly kind and helpful upon our arrival, helping us into the flat and suggesting local things to do.
If this apartment is free, you should grab it.