Personally, I feel perfectly entitled to rate the race as a 2.
After all, the prior expectation of Monaco is that it is going to be a boring snooze fest- so when something unexpected happens, it makes it a much more exciting race.
In Montreal, there is the expectation of accidents, overtaking, safety cars etc, so when you get a "dull" Canadian GP, it has failed to live up to expectations, and can expect to be rated in such a way.