My DC goes to McGill.
Pros:
Montreal has a vibrant arts community, so it's an amazing city for any kid involved in the creative arts (visual, music, film) - my kid is arty and recently mentioned to me that people say that this is the current "trifecta" of cities from an arts perspective: Berlin, Melbourne, and Montreal. I've had someone in the art world remark to me, after hearing that my kid is at McGill, that "Montreal today is like Berlin in the 70s." Meaning, a creative hot spot. Anyway, it's a great environment for an arts-oriented kid to be in.
Montreal is a very affordable city, with rents and food prices well below what one sees in NY and DC. It is safe (b/c no guns!) and lively. It's a very park-oriented city, and every park is filled with families, people reading on blankets, etc. Also lots of cozy cafes. With the parks, cafes, charming neighborhoods, and le French everywhere, it feels very much like Europe. French is NOT required for McGill, my DC has friends that never studied French and they are just fine.
Montreal is not so far! Only 1 hr 20 min flight from DC. If your kid is looking at Boston/New England schools, it's really not that much different.
McGill overall is a good school. My DC has had some great classes, some meh classes. Some small seminars, some ridiculous lecture-hall classes with hundreds of students. But overall, enjoyed it. Like any big public school, it's bit bureacratic -- but it teaches kids to navigate the system and advocate for themselves. Kids love off-campus housing and living the independent adult life. Most freshman live in dorms, but after that, they are happy to be off campus. There's an active rental community, and TONS of good housing.
McGill is very affordably priced - plus historically the exchange rate was pretty favorable to the US dollar. It came in at just a bit higher than instate tuition for us.
Cons:
The winter. But, my DC recently said that the winter is not that big of a deal...the kids don't mind the cold like we old'uns do.
Getting the visa thing and currency thing sorted out at the beginning of freshman year takes some navigating...but it's doable and there's a very helpful community of non-Canadian parents on Facebook that helps each other out.