I would give her an A-. Her best line (paraphrasing) was, "I'm not going to give answers that the moderator or opponent may like; I'm speaking to the American people."
She was prepared, and somewhat relaxed. The perception was that she did very well for a raw rookie. That's all that matters.
I thought her best line was when she said, to paraphrase,
“You attempted a lame joke, but it didn’t work, because nobody laughed.”