Very well located flat on the first floor (which is convenient, as like most Paris buildings, this one also does not have an elevator). It is spacious and modern and pretty well equipped - we didn't really use the kitchen and the washing machine, but they are available in the flat.
As others noted, it can get a bit noisy because it's on the 1st floor, even though the street itself is quite small - but to me it seems like a normal noise you should expect when living in the centre of a busy city. It can also get a bit stuffy in the summer, as the windows are only on one side of the flat (two small fans are provided).
Overall, the location, space and cleanliness made up for the bit of noise. Since we hardly spent any time in the flat itself, and there are so many great places nearby, it is a flat I would recommend as a good base for exploring the city.