That being said, there is still a lot to hate about Paris: dirty and overcrowded subway, shady people everywhere, especially around tourists' places of interest, etc. Not that much different from big cities like NYC, SF, Seattle, etc.
I felt safer in Paris, LA, and Seattle than I ever was in NYC.
If people see you making the effort, they'll switch to English, in my case, anyway. But you have to show some respect, first. You have to let people know you understand you're a guest in their country.
Of course, this was many years ago. Things may be different now. And of course, if you're going to live there you're going to have to learn the language as quickly as you can.
I can only say the most basic phrases in French and have experienced zero problems.
I don’t like to be the ugly American who just assumes the world should speak my language, so I was ready for language barriers, but I had no real issues at all.
Now it's true that Americans tend to love to frighten each other with firecamp stories about the Big Bad Frenchman, but IME it's mostly a mix of latent francophobia and a grapevine of bad experience between what is locally perceived as wholly uneducated Americans and local Frenchmen that the Americans tend to see as arrogant.
The latest if most often due to (i) tourists forgetting that what is a great week you spent years saving for is another Tuesday for the other guys in the street, (ii) many fundamental French etiquette rules (don't shout, say “hello” first when talking to someone, the absence of a hierarchical relationship between hospitality personnel and customers, distant behaviour is not arrogance but a mark of respect, etc.) are completely accessory in the US customs, leading to very strong misunderstandings.
So book a trip for a week and come say hello, we don't bite! (and avoid like the plague any café/restaurant in the touristy areas)
These two are generally adhered to in the US as well. May be the hierarchy part is there if you're staying at really exclusive resorts. But by and large, most folks are polite.
There is obviously the random asshole. But those exist everywhere.
I'm not sure; granted I did not visit a lot of places in the US, but when I was there (Miami/Denver/Phoenix), I virtually never saw e.g. a customer greets the cashier when buying things.
A few times someone would correct us (eg "after 6pm we say bonsoir instead of bonjour"), but it never felt like it was done in a dickish way and people were generally pretty accommodating. Perhaps it helps that I went to Paris with low expectations, not thinking it'd live up to the hype, but I had a great time. Definitely don't let the language thing keep you from going!
It's safe to assume you'll encounter a very wide variety of people speaking many different languages.