I have no opinion -- none at all -- about whether Caroline Kennedy would make a good senator. But for someone with a law degree and now political aspirations, she's astonishingly ill-spoken.
No, Caroline, we don't know
It's not necessarily admirable in consumers of political rhetoric like me that we focus more readily on "um"s and "you know"s than on what the person is saying. But we do, and it's no surprise that we do -- English teachers and speech coaches have been making this point forever.
I never whaled on Sarah Palin for the way she talks, because there isn't much reason to suppose she could do better. She doesn't have a fancy education, and she doesn't come from a place that's world-renowned for its intellectual life. But Kennedy is a different story. She has the best education money can buy and every possible reason to know what accomplished public speaking sounds like. And she still sounds like a dope, because of those "um"s and "you know"s.