I hate to go for the easy target...
She really, really, doesn't have the experience to be president. You know it.
Her trooper scandal has legs.
She directed indicted Senator Stevens' PAC.
In a widely distributed video clip, she avows that she doesn't know what the Vice President does.
Her 17-year old daughter is pregnant, unmarried. The father of the child (OK, I'm not sure of the details of Alaska's statutory rape laws) is a rapist. (I don't believe the rumors that Palin's young baby is actully that of her then-16-year-old daughter)
Her choice by McCain seems to be a botched, compromised, choice by-committee. It really shows how poor McCain's judgement is, and how poor his leadership skills would be as president. This may, in fact, take down the candidacy.
Agreed, she has led a campaign for part-time mayorship, and governorship of one of the United States. She speaks clearly (but is too dull to know how to pronounce the word "nuclear..." do we need another president with that deficiency???). She walks the conservative walk in her personal life to all accounts.
Another Republican failure, and an American failure if ~ half of the U. S. continues to support this failing party.