Caroline and Jérôme were really nice and tried to help everything they could. We made some mistakes but they forgave us generously.
The room was a little bit small for us because we had three big luggages but I think it will be fine with one or two people. The wifi was slow and have disconnected quite often, so we couldn't use it for several hours at the second night.
The location is excellent; really close to train station and subway. We didn't need to walk that much to get close to the city center. But it could be a bad point too, because the trains (or maybe trams) run till late night, so the noise is a little bit annoying. But it's okay if you close the window! There's no a/c but one fan. If you are three, one should sleep in another room. It means someone (maybe two) should sleep without a fan in summer.
Anyway, we are quite satisfied with this place. Thanks again to Caroline and Jérôme for their kindness.