There is no denying that you will work very hard to succeed at this school. It is highly competitive, and requires a very high level of motivation. That being said, you are surrounded by outspoken and intelligent peers, and forward-thinking, passionate, and world-class professors. I am very satisfied with my experience at McGill and Montreal in general.
One thing I would like to point out is that the administration at McGill is abominable. If you are trying to see and advisor, access health services, or Service Point, you will inevitably wait a long time. Everything is so bureaucratic that it is impossible to get a simple and concrete answer from anyone that is not a professor.