The 2010 Nav system is abysmal. Having recently traveled from Chicago to Phoenix and back, I can say that the next time I will take my Garmin along and use it instead.

Someday I'll catalog all that is wrong with it, but for now here's a few:

(1) It often confuses what city things are in. If you want some fun, try looking up a hotel in Van Horn, Texas, and then route to it. It will then show the street addresss as being in Kent, Texas, all the while actually directing you to Van Horn, while telling you it is taking you to Kent (Van Horn and Kent are about 40 miles apart, so it's not like a suburb or anything).

(2) Several times the Nav randomly announced "prepare to turn Left" or "Prepare to turn Right" while the map showed absolutely no turns on the route for at least 25 miles ahead.

(3) Often fuel stations at exits were not shown accurately, with the Nav locating them smack-dab in the middle of the interstate. As a result, it would not tell you to take the exit. Clearly Teleatlas did not have the actual GPS coordinates of the stations, but just the exit number. So they just located it in the middle of the interstate at the exit location.

(4) The POI database is very poor compared to Garmin and others that use Navteq, rather than Teleatlas data. TeleAtlas is European-based, so I suspect BMW swithed to them from Navteq for the new GPS as their European data might be better than Navteq's.

I can only think of four advantages the BMW Nav has over Garmin:

(1) The screen is excellent, both in resolution and visibility in all light conditions,

(2) The Zoom function with the rotary dial is quite easy to use and quick, compare to the Garmin touch screen,

(3) It is linked to the audio system, so it will lower the entertainment volume when it speaks, and

(4) being built in, you don't have to store/hide it when you stop and leave the vehicle.