Sébastien's place is in a great location, very close to the train station and a walkable distance from the Notre Dame Cathedral and other locations.
Sébastien was always very responsive, helpful and friendly and there was absolutely no issues sith our stay. His flat is in a busy area, but it didn't bother us at night time, as when you close the window almost all sounds are gone.
I would highly recommend staying at his flat! Just try to avoid the neighbour.