This is a very central apartment - it has a fantastic view over the square (which made for some lovely sunrises) and is very easy to get to/from. It's just by the metro station and a short walk from several major attractions. The apartment had a very cosy feeling, is in a beautiful building, and has a well equipped kitchen. The check-in process was very easy, as Marie's cleaner was waiting to meet us after our train arrived, and Marie communicated well before and after our stay.
There are a few things that I think other travellers should bear in mind before booking: 1) the central location made the flat very noisy and bright at night - there is a constant buzz from people in the square and trains and there are no blackout blinds. 2) There are quite a lot of stairs - this didn't matter for us, but there are full staircases to get to the lift on the first floor, and from the lift to the flat. People with mobility issues would struggle. 3) The host has a lot of items in the apartment. I've never encountered this when staying in a whole-home rental, but most of the wardrobe space was taken up by their clothes and there was no room subsequently to put our own luggage or unpack properly. 4) There was a small amount of mould in the corners of the bedroom and lounge.