Hello,
That's cool that you had success just plugging it in and it working. Really nice to know.
If you are going to sign up for a Sirius account, and use the Nav, I find it well worth the money. It gives you the Travel software and you can find gas stations with current prices, weather, poi locations, etc. I use it all the time. I especially like the live weather map and the gas station price feature. I recently updated the software for the unit from the My Ford website and the voice function seems to work better, and there is a reboot option.
I also spent the money and bought the discs from Ford for 149 and it included the Gracenote music info. I don't know if it was worth it, but I travel a lot to new places and it seems to be working well. When buying this it asks for the serial number of the unit and provides a unique activation code. Now that I have it installed I have the 4 discs that are probably usless, unless someone knows of a way to generate a code for activation. Did the one you bought online work??