Aside from a fear that we will have a new note design every 6 months, like some coins (25c), the issue I see as the biggest is that of counterfeiting.
If the public did not know every single detail of every note, then it would be a dream for counterfeiters. They could slide in some bogus notes because people would not know A from B from C. It seems to me that printing a note (although very elaborate) is much easier than punching a counterfeit coin. I think it would be a criminal's dream, and the RCMP's nightmare. Maybe I could get a job in their (RCMPs) counterfeit unit finally (if there is anyone reading this that has any pull, give me a message.
In summary: I would expect a monstrous increase in counterfeits. That's bad.