Quality wise, I heard AM sounds like FM and FM sounds like CD... however, I don't know anyone with a unit, so I'm speaking on hearsay. However, I listen to some HD stations over the stream. Here's a link to all of Clear Channel's HD stations. Even the Columbus stations' are on here. It's nice, cause it's like satellite right now, with no commercials. Makes the day go by faster at the office...
http://www.clearchannelmusic.com/hdradio/