I have had my 2011 LTD for a little over a week. I love how it drives and there are a ton features I have become enamored with (MFT, adaptive cruise, BLISS to name a couple). :happy feet:
On the Nav, I have not found that you can download routes as you note (if you can post a link/instructions, that would be great).
I have never had a car with Nav before, so I have no comparison, but here is what I know. With the features that I think are tied to Sirius, you can locate Points of Interest (POI) such as a park and such. The Nav systems has a great "3D-ish" view that actually shows major POI buildings (I was in downtown Denver and Coors Field (Rockies stadium) was a big 3D land mark on the map.
Great traffic features that have already helped me avoid traffic. Better than my Google maps app on my iphone. Great voice activation features.
Very nice feature with next direction able to show on the right dash mini-LCD next to speedometer.
It uses your contacts as you are setting destinations (via voice) if you ou have as contacts address uploaded, it will zero in on that saving you time on destination entry. I have yet figure out how to say "Destination, Mom's House" (assuming Mom's House is a contact) to set a destination and had to build destination manually via voice (driving) or key entry (if not moving).
So far the Nav helped me find some back street short cuts on routes I have been driving for years that saved me some time.
I did have the Nav lock up and cause a Windows error in the Myford Touch this weekend, but it rebooted itself and kept my destination in memory....once it rebooted it kept my route going. I will assume pending software patches should stabilize...but Sync is a Microsoft product so I am a little skeptical and await a Blue Screen of Death someday (kidding..mostly). Note: lock up did not impact car performance or handling, simply entertainment and nav were down for a few minutes (climate still works via console buttons).