Not simply having flaws, but showing how the character can deal with them, and overcome and/or learn from them, I think, is one element that can make for a truly interesting character.
I'd say this is a fair asesment. The problem with TV today though is that characters have flaws for the sake of having flaws, and don't learn from them or try to overcome them.
Writers (and viewers) seem to have a problem with heroes anymore. I have no idea why that is.