She was, in one sense, one of a group of terrible VP selections...although not, I think, as bad as Nixon, Agnew, Quayle, and Palin. She was selected out of nowhere, and the vetting missed important things that made her ride in 1984 a very bumpy one.
Not that it mattered, of course, as far as winning or losing in November that year. And, in my view at least, she handled the process well. Despite both her own rocky candidacy and the ticket doing badly, I don't recall anyone then or later ever pointing to Gerry Ferraro as a reason that women shouldn't, or even weren't, advancing nationally.
She never, unfortunately, found a way to build on it. Her Senate campaigns were as uninspired as Nixon's gubernatorial campaign (or Quayle's presidential run) were, and I found her TV appearances or op-ed columns mostly lightweight (at least until the 2008 Democratic primaries, about which the less said the better). My best guess is that she was just badly miscast as a national figure, but probably, as far as I know, would have been at least a solid and perhaps an excellent Member of the House. She certainly could have remained in her seat as long as she liked, and it's hardly impossible to imagine her as Speaker had the cards dropped right (not, to be sure, an original observation, there, but one that's important in understanding her career). Among other things, her career is a reminder that even the best of Congressional insiders (and few are the equal of Tip O'Neill, Ferraro's big supporter in 1984) have a history of utter cluelessness when it comes to presidential politics.
But then again, in 1984 there weren't all that many women available (or at least logical choices) to be the First Woman Vice Presidential Nominee.
All in all, I think that as much as it was in some ways a bad choice, in more important ways Walter Mondale made a good-enough choice.
She was, all in all, a great American, and she deserves to be remembered warmly.