Originally Posted by IanB2

Factory stereo is fine sounding, but lacks in the ability to play MP3's, attach a thumbdrive/SD card, stream from your phone, handle bluetooth calling (on the pre-'06 anyways), etc. The nav is in many cases in excess of 10 years old and updating maps can't help that. The problem is that it's no easy task to upgrade if you have factory nav/ML Audio, so you're stuck with an above average stock stereo, which is a big drawback for many. If you don't care about that kind of thing, then it's a non-issue.

There are add-on units that help (bluetooth & USB input), but I've never really been that impressed with the GROM USB2 unit I purchased, the wife can't figure it out and it's sat installed, and unused for over a year now. Maybe the other alternatives are better?