There's a prior thread on the nav you can google for. Personally, I
love the nav.
Regarding mp3 players, once I signed on with satellite radio, I found
myself in no need for MP3's. The reason I previously used MP3's were
1) not liking the type of music on the radio and 2) hating commercials.
Both were solved with satellite, and now I find it an inconvenience
having to download, arrange, and burn MP3's. The Accord nav includes a
6 disk in-dash changer, so you have the opportunity for 60+ songs if XM
doesn't satisfy you.