Yes you should be as confident as possible.
In interview, you can admit that you used to have flaws, which you identified and corrected, but this is as close as you can get.
Why do you think so? I would personally like more people who are actively talking about their good and bad sides, although I'm not sure if I'd do that in an interview, because it might mean they don't know what appears to be the most effective strategy.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.