Consider that Palin has had just five weeks to get a grasp on DC issues and debate them before the entire world (and roughly two-thirds of US voters, according to reports of viewership). Given that short time frame, I'd say she did damn well.
Nobody who is elected president has the instant qualifications to be president. Governors are more often elected because they have experience running a government rather than debating it. Alaska is not a huge state, but neither is Arkansas.
I'm extremely impressed with Palin's ability to get a handle on the issues as quickly as she has, and confidently go up against a seasoned political pro like Biden. If she can do this on such short notice, I'm sure she'll do fine if something happens to McCain. It's not knowing the details of amendment 5(a) to SB105 that matters, it's the way a person's views are shaped, and how he/she uses those views to articulate policy. On those points I think Palin is solid.
And it's true that McCain has to hit hard. He has two more chances to look Obama in the eye and tell him and the American public that Obama has been lying. It's time to call Obama for what he is: a self-absorbed socialist charlatan who will wreak havoc on the economy, on defense, and the future of this country.