In Canada possession for the purpose of medical consumption is legal, if recommended by a doctor, approved by health Canada(the equivalent of your FDA).
Medical Use of Marihuana - Main Page <--further medical info
try to ignore the fact that they spelled it wrong...i donno what is up with that.

In terms of recreational use, if you are caught in possession your punishment will probably be determined by your quantity. And your honesty.
If you lie and lie and they find it, police are more likely to charge you. because they can.
If you get caught and know you are caught..tell them. They will take it and send you on your way.
Of course police discretion is never completely predictable...there are nice and shitty cops.
And of course if you have a shitload and are caught, and trafficking is involved, they will most likely fine and/or charge you. I doubt however that jail would be involved. You can swing stuff with lawyers usually. And judges see a lot worse than pot in the courts...
The rules on growing have taken a turn to the right though. "Steve" has made it very hard to escape jailtime when caught growing. He has also done more to harm the marijuana movement by trying to enforce more punishment for simple possession, though I haven't seen this put to work...overall, it is illegal but some/most times they don't do much but take it away.
As for the coffeeshops I can't say, never been. But I hear they are there...

Point is we need a more left wing government to make any progress. But it sure is better to be caught with herbs here than somewhere in America...