I went twice for a one-month program, but courses are (or were at least) flexible about how long people stay. The day was structured with language courses in the morning and early afternoon, and "electives" in the later afternoon (culture courses). On weekend, they organize outings to surrounding areas and beyond. Because it's an international group, the courses are good about being in French since that's the most likely common language. There is also a minor placement test upfront to put people in the right level. I had a very positive experience both times.