Your experience in France will depend a lot on where you go, luck, whether you make an effort to speak the local language, and obviously on your own personality. The French are quite dour by nature, there are even studies on how French people tend to focus on the negative. It's a cultural habit to complain and see the dark side of things. If you're a human golden retriever (i.e. friendly) American they're going to love you because it takes them out of that. The stereotypes on locations also don't necessarily hold very much. You could find very friendly people in Paris, but have bad experiences in the south. Generally speaking the South-West area of France is considered the friendliest however.