Just out of curiosity, why did you decide to get an aftermarket head unit?
Didn't like stock?
Stock went bad?
Wanted something new?
Wanted something custom?
Something else?
As for me:
I got an Alpine headunit because my stock was literally skipping, just because I'd be going up a hill. It sounded really good for stock, with a nice interface, but it was just too annoying to not switch.
I then made the move to the AVIC-D3 in February because I was going on a long trip and needed GPS. Originally I was going to get a portable device, but I found an authorized dealer selling it with the iPod kit for $375. After the rebate, and sale of my Alpine Unit and iPod kit, I only had to pay $25 for it.