I'm not sure. I think if there is any drawback to this pick, given what little I know about her, it's that McCain is near death and this woman just doesn't seem very presidential, she comes off as being kind of middle-management. She ain't no Hillary.

If the democrats can make this election seem pivotal enough (they can) and she comes off as being a trophy-candidate (in the sense that it becomes obvious she was picked mostly for her gender...don't put anything past those republicans) the democrats could essentially scare enough people into doubting her ability to take over if McCain croaks.