BMW Nav systems

From the very first Idrive BMW have been universally slammed for the systems lack of user friendliness.
My 2007 7 series (my 13th BMW) has one of the worst Nav systems ever. What good is a system that at large zoom in scales shows no street names or a few letters of a name sliding out the edge of the screen?
BMW blame the mapping suppliers so I contacted both Navteq and the new supplier who both say they supply the maps with all the information but Munich decide what information to put on the screen.
Paying $199 every year for the same limited info isn't very clever!
Does anyone know of an aftermarket upgrade to the standard system or a way to replace the nav feed to the standard screen more informative without making the other information one can select on the screen unavailable?

You can replace the nav feed but would require a new NAV system and it wouldn't interact with your steering wheel or idrive buttons I would think.