The sector is quickly developing, as new Federal rules kicked in April 1st 2014. It is important for investors to align themselves with companies that will actually deliver. There are several market figures floating around, but safe to say the market will grow exponentially over the next 5-10 years. Early exposure is likely warranted. Only 12 licenses have been granted to date, with Health Canada indicating more would be issued.
For context, in the US, more states plan and/or will pass the legalization to allow medical and in some cases recreational marijuana. Twenty have legislation pending and the market is forecast to hit $10.2 billion in less than 5 years.
There are currently about 40,000 users of medical marijuana in Canada.