I don't think the fact that she is overly bias and driven by agenda really diminishes her credibility at all. Just based on the fact that she cites the facts she uses and has a larger breadth of knowledge than 10 New York Times writers makes her one of the more credible writers of out time. Granted she can easily be viewed as one who disagrees w/ liberals just because their liberals, but that wouldn't be an accurate statement. Many people take her tone as whiney and overly critical, but I think it really turns the tables on the liberals. Liberals are typically the ones who whine about the issues and are overly critical of Republicans, and when the tables get turned on them (many times, she is merely jesting), they go bonkers. I don't think she would be as good a read as she is if she did not put the liberal perspective in such a humorous light. I think her aim in doing so is to not to just wax poetic about their faults, but to highlight the idiocy of many of their views.
I've read her weekly columns for about a year now, and only on about two occasions have I taken issue w/ the way she said something. One article in particular was about a week or two after 9/11/01, and I think she jumped the gun on some Muslim issues (if I remember correctly).
I'd rate her at about an 8.5-9.0 in credibility.
I like the fact that she's a syndicated writer, and not really anybody's puppet, like many columnists and reporters. She seems to have a VERY one sided view of the world, but at least she can coherently tell you why she thinks that way.I get chills every time I think of her interview w/ Katie Couric on the Today show. She did so well, and was such a great sport. She got Katie's panties all in a not.