I highly recommend a piece in the current New Yorker on the great Ralph Stanley. It is by a senior Newsweek writer named David Gates, and I think he has a real feel for what makes Dr. Ralph special, as well as being a fine wordsmith. I particularly like this observation:

Good bluegrass -- like good blues, good jazz, and good rock and roll -- is sweet and sad, wild and sexy. Mediocre bluegrass, which you can hear at any festival from a dozen perfectly competent parking-lot bands, is among the most wearisome music on the planet; the more it tries to stretch it's parameters -- with arty lyrics or bebop licks -- the more evident its limitations become. Ralph Stanley understood that the way to go was to simplify, intensify, countrify.

Couldn't have said it better myself.

The article is surrounded by way overly-serious pieces on hip-hop, Radiohead, and other flotsam of the contemporary music scene, but it's well worth the read.