CNN has a webpage called Debate Report Card where you can read what grades analysts gave the two Vice-Presidential candidates for their debate efforts. Sarah Palin got 2 A's, 2 B's, and a C from the analysts, while Joe Biden got 3 A's and 2 B's.
Then, at the bottom of the page, you can assign the grade YOU think the candidate deserved. The average of 43844 grades for Sarah Palin was a D. (I gave her an F.) The average of 36,001 grades for Joe Biden was a B.
CNN also has a page that analyzes the language of the debate in much the same way you can get a document analysis in Microsoft Office - ease of reading, grade level, passive sentences, etc. Palin used the passive voice more often, which the analyst says means she "deflected responsibility."
Here are some stats from CNN's language analyst:
Grade level: Biden, 7.8; Palin, 9.5 (Newspapers are typically written to a sixth-grade reading level.)
Sentences per paragraph: statistically tied at 2.7 for Biden and 2.6 for Palin.
Letters per word: tied at 4.4.
Ease of reading: Biden, 66.7 (with 100 being the easiest to read or hear), versus 62.4 for Palin.