We plan to use eTA as a tool in the case of temporary residents, where we don't have a backlog. There are some processing delays, but as you mentioned, we expect that, for the vast majority of applicants, the eTA system will make it possible to make a decision in a few minutes. As for people who must see a visa officer, the delays will be fairly short. We are talking about two to three days to hold a meeting to clarify the eTA decision.
On November 19th, 2012. See this statement in context.