Its not too bad. I upgraded to an aftermarket unit when we had a '12. You'll need the radio, the appropriate dash kit, harness and a steering wheel adapter if you want to keep that. If you had BT originally the OEM mic will not work with the new H/U, but you can put the new mic in the OEM location with a little effort. There should be more than a few threads in the 4th get forums if you need more information.
I used an Kenwood Excelon unit, a DNX940 maybe (I can't remember the exact number). If I remember correctly I did a write up in the 4th gen forums if you search for it. Some of the info won't pertain directly since I had a '12.