I fully expect that it will have to be redone within a few years. In the federal legislation and most of the provinces the legal age is 19. The new government in Quebec and possibly the government of Manitoba want to change that to 21. I can imagine the line up of vehicles full of 19 and 20 yr olds from Quebec headed to border cities in Ontario and New Brunswick for their weekend supply.
The legislation also allows people to grow up to 4 plants for their own use. Manitoba, Quebec and one of the northern territories don't allow residents to grow their own. In Manitoba, growing a plant will cost you a $2500 fine - the same as moonshining.
There is no reliable way for police to test for impairment and there isn't a big enough supply of even the doubtful devices to go around. Nor is there an accepted standard for impairment.
In Manitoba there is almost no place you can legally smoke except your own property and National Parks. Great if you own a house but apartment dwellers are SOL. And you can't smoke in a provincial park, beach etc or anywhere else in public.
Distribution centres are warning of national shortages - for as long as 6 months in some provinces. New massive greenhouses are being built but they are months away from producing a bud.
Only a small fraction of the legal outlets will be open on D-Day and some don't expect to be operational until well into next year.
Any notion that legalization will reduce the police workload is wishful thinking.
And these are just some of the problems.
Legalization is a wonderful idea. But it will have some problems anywhere it is tried. We should have done a much better job of it if Canada is the place that other countries are looking to for a plan for legalization.