I have the BMW nav and it is not as user friendly as the Acura unit, so I am told. There are too many features to go into here. However, it works fine for me and has never let me down as far as directions are concerned. My wife is terrible with directions and the unit has saved her many times. Any time I am in an area foreign to me, it is invaluable. The interface is a little cumbersome in that it uses the knobs for data entry (turn to scroll, press to select). Either way, touchscreen or knobs, you have to take your eyes off the road to enter information. The new 5 series has an optional head-up display that solves this problem, but it isn't in the current 3-series. It auto saves your last 20 destinations and has a separate address book (20 locations as well I think).
The maps are very accurate and the info database is extensive to say the least. If you have any specific questions, please ask.
I don't have the bluetooth module/software, but some on here who have it describe it as awesome. It is integrated into the display and controls.