Compact Flash is good because of large size. That's a given. However, it's bad because it's very, very slow; and it only gets slower. I owned a CF based RCA Lyra a while back and after maybe a week of having the same song on theplayer I would have to delete and re-copy it so I wasn't waiting 3+ seconds for the song to load......as opposed to the normal 1 or so.... Similarily, SmartMeda, SD and MMC do not have these problems. Because of this, nobody makes CF based players anymore, because they're slow as all hell.