Well, I guess I'm all alone in this, but I LIKE the nave system on the '07.
I personally prefer the voice prompts and the simple directional arrows. I have advanced nav systems in my other vehicles, including the new one from GM with the built in back up camera. They are cool and I enjoy them, but I just prefer not to 'clutter' the dash of my bike with a lot of aftermarket stuff. I like the functionality of the system and the clean look by having it built in.
Personally, I think Harley will eventually increase the size of the screen and add color NAV to the factory radio, but until then, I plan to stay with the factory system.