Just got back from a couple days in Quebec City (and a drive through Montreal). There is a little language barrier, but not really. Most people know english, even in Quebec City where most can at least understand the basics. The only trouble we had was with a local bartender who admitted she was poor with English and we essentially used hand gestures and a Tim Horton's in Trois-Rivieries where the cashier had to get someone else to take the order. Heck, even a druggie asked us if we had cocaine in french and then english - I'm not even kidding.

I'm really bad with even trying the basic french greetings/responses. I finally got used to saying "merci" but nothing else. It was fine, most people laughed politely at the awkwardness (especially waiters who greeted us in french and then had to change over to english). They were very interested in us as well and quite chatty for the most part.