Joe Carter explains why NPR is objectively better than commercial talk radio. I agree with almost everything he says. Part of it is the commercial element and the fact that callers have nothing to say. Callers on NPR vary, but many of them have real questions of shows' guests or engage in a real discussion. Hannity, Limbaugh, et. al. are just looking for dittos from unthinking thralls or a punching bag at whom to rant. The people who fill these roles seem to fill them admirably. Those drawn to call such shows are exactly the type the hosts want calling. Anyone with anything intelligent to contribute just doesn't fit the format and won't likely be listening anyway.
I also agree that the biggest strength of NPR is that it isn't all about politics and the "us vs. them" mentality. They discuss issues that are interesting to me, and they discuss things I find utterly boring, and then there's everything in between. However interested I might be, it's pretty clear that the people talking about them consider the topics interesting in their own right. The interests of Hannity, Limbaugh, et. al. aren't exactly very broad.
The biggest downside of NPR is not the fact that virtually everyone working for them is politically liberal. The liberal viewpoint is worth discussing, and there's no way anyone will be able to criticize it if it doesn't come out, so conservatives should welcome the voice of liberalism for the sake of better dialogue and more fruitful discussion. Joe is exactly right that the biggest problem with NPR is that many of its key people are just so out of touch with many in mainstream America. As Joe says, "The hosts of All Things Considered, for example, would have no trouble relating to an obscure avant garde musician, while a popular gospel singer would be considered an anthropological curiosity". That sounds right. They bring Rick Warren on and are amazed that he points out the three biggest surprises of 2004: Mel Gibson's The Passion of the Christ, Warren's own The Purpose-Driven Life, and Bush's reelection, none of which make any sense to the cosmopolitan, left-of-center culture of blue-state secularism or liberal-secularized religion. Hannity and co. are just as out of touch with blue culture, and shame on them, so both parties in this comparison have that problem. NPR gets the advantage, though, because of what they talk about and because they do attempt to understand Rich Warren and seek his opinion for its own sake, with what at least is an attempt at a viewpoint-neutral perspective. You don't find that on commercial talk radio.