That's an interesting deal for SXM.
I am a subscriber and love it on long road trips, but have stopped listening on my daily commute. There are WAY too many channels, resulting in absurdly lossy compression. Classical music compresses easily, so that doesn't sound too bad, but try something like metal - the artifacts created make it unlistenable. I realize most people don't care about sound quality.
I used to be a Pandora subscriber, but their catalog and playlist algorithm is shallow, for my tastes. For newer pop, it's an interesting way to discover new music, but try creating an "Artist Station" from Frank Sinatra and you will hear Bobby Darin's "Beyond The Sea" about 20 times a day. Lots of repetition. Again, most people don't care.
With newer cars featuring dedicated internet connections, and built-in Spotify Connect, both services will soon be dead. Spotify really was visionary with Spotify Connect - my kid can bring up the app on her iPhone and "drive" the Spotify app built into our car. And, once you get used to skipping a song you don't like, or replaying one you do like, there is no going back to linear programming.
I *really* wish the BDP had support for Spotify Connect, but I can only dream...