It is extremely easy for people to immigrate to Canada. A former co-worker went to university at Wayne State in Detroit, lived in Windsor, ON, maintained his Canadian residence while he finished his PhD and then his post-doc at American universities. He applied for Canadian citizenship as soon as he could (I don't remember exactly how long it took, but it was somewhere around 3, 4 years) and he got it without ever having worked or having a job offer in Canada, or even attending a Canadian school. Ridiculous.
The health care system is not free- you don't pay at the point of service, but you pay in other ways, such as higher taxes, lower wages on average than in America, and much, MUCH longer wait times. And, you still pay for dental, and at least in NB, prescription drugs are more expensive than what I pay here.