I don't have specific evidence, but I am confident that seeing a VP's mannerisms and confidence (or lack thereof) during a debate has a huge impact on how people view the actual presidential candidates. I think most people realize that we rely on a VP if the Prez actually falls during his service. Yet, in this particular election, I thought Biden did horribly, and yet it didn't seem to kill Obama in the election.
The vice presidential debate will not only be an interesting debate but, will contribute a lot to the affect on the coming election. Debates in my opinion are where the most voters are won over because of the convincing views that the candidates have. Most voters base their vote on the candidates views and not looks or personality.
It'll be entertainment for me. Beyond that, it's interesting that Biden will be appealing for a second term, but Ryan will be appealing for his future beyond this election. I reject the jerk Ryan, but I will be interested in how he does. If he does as well as Romney did, I will bite my nails and fear for our future. I hope Biden destroys him.
The Vice-Presidential debate has never really mattered very much, and this year should be no different. People vote for the President, not the VP. While a particularly egregious VP may turn some people off-- Sarah Palin comes to mind-- in general, the Vice-President is just sort of there, and doesn't matter nearly as much as the President in the decision of whom to vote for.