I have it and use it a lot. My job also takes me on the road a lot and it is easier than trying to hold a map and drive. Beyond the NAV I happen to love the iDrive and the expanded screen, especially for displaying my musical selections.
Current: F30 328i Sport Line Sapphire Black|Black-red
Retired: '09 E90 335i M-Sport AW|Oyster, '07 E92 335i Graphite|Saddle, '05 E60 545i TiAg|Black, '01 E46 325i Jet Black|Black