I had XM through my Pioneer headunit/tuner in my X and loved it. When i got rid of the X and bought the Impala without it, i went through withdrawl. I just had an aftermarker XM Commander installed temporarily until the plug-n-play tuners become available for the new Impala.
I do agree that they play a lot of the same $h!t all the time, but that's probably b/c i listen to only 10 music stations out of the 100+ and i'm only in the car for a total of 60min/day, so i may hear the same songs on the Top 20 @ 20 station a couple times a day. Oh, well - that's when you dial up another.
I used it in the adirondack mountains while we camped and it never lost a signal, and listening to the Yankees games at the campfire was sweeeeet.
XM Online is great, too.