Personally i like the Sirius Unit better. For the same monthly price and for a lot less than replacing an entire head unit, it can pause and rewind thru what you're listening to, you can browse channels by categories and see whats playing without changing the station your on and you can set-up alerts for artists, songs, and sports teams. My girlfriend just got a new Hyundai with built in XM, and was a little dissappointed at the features it was lacking. It's like having HD Cable but not having a cable box to show you a guide.