There's such a lovely versatility and flexibility to this program. Personally, I was lucky enough to be have the perfect placement with my host family but I understand reality happens and this can seem scary to some people. However, I assure you the risk is worth it. If you are a positive and open candidate you'll absolutely love it!
So first off, Montpellier is a wonderful city. To me, it was just big enough to be urban and fun without the typical drawbacks of a big city. The old part of Montpellier, which is also the majority of its downtown core is a pedestrian zone and its really well connected with the tram system as well as trains/busses to nearby cities like Nîmes. There are tons of parks, cafes, shops to visit and while I was there in this past spring there was an arts, music, culture or even extreme sports festival on the weekends.
As I mentioned, my placement was superb. I was living right in the downtown core, a five minutes from central station and about 40 minutes from the beach. Not only that but my host family was really genuine, kind and fair in terms of hospitality and their expectations of me as a live-in language assistant. I had a wonderful experience thanks to them as well as Soizick and Naïa who were so helpful and accessible along the way.
I had an incredible time doing this program. With cultural exchange, however, I believe you get out of it what you put in. So if you're ready, go for it! It would only take a bit of savings, some effort and a open spirit.