I've visited Mont-Saint-Michel. I hated it. It was a very humid day with no wind. There was so many tourists getting off buses. The streets were very narrow and cramped with houses and a couple of places to eat at either side and hundreds of tourists everywhere! It was so tight and crowded that you could barely move sometimes. We had to stand (from the middle-lower streets) in a line for TWO HOURS to get up to the castle with no water! We struggled to find somewhere, a shop where we could buy water.

But don't let me put you off. If you wanna go, go. Just don't go in August or on a humid day.