My colleague is an American postdoc even though her current salary is lower than she made in the same position in US. She chose Canada because of the safer sociaty, better environment and better opportunity.
The negative viewpoint of Canada may come from the reality that:
1) none of the major political parties considers the economic development as the first priority;
2) extensive labor union protection in Canada.
We can not judge Canada by simply yes or no. Each person has his/her own background, opprotunity and luck. I am one of US GC holders working in Canada.