Now that I've been listening to XM Satellite Radio for a while, there is one thing I've noticed that can be a bit annoying. XM compresses the audio so they can provide more and more channels on their existing bandwidth. The downfall is, of course, the more compressed the audio, the poorer the audio quality.
It is especially noticeable on the talk channels, but the music channels also suffer. (and the city-specific weather/traffic channels are nearly incoherent) XM says they've been "experimenting" with different audio transmission techniques, possibly causing the poor audio quality. Here's hoping they will launch another satellite to increase bandwidth and thus allow for less-compressed audio. I'm sure XM has plans for adding more and more channels, and hopefully they won't make room for them by further squishing the existing channels.