My belief is that any tech item that is dependent on a certain piece of hardware (iPhone 4S or lower) is not worth it for a car... backward thinking. That is, unless you plan on keeping the car for only 2 years. When I heard that the Apps were only available on the iPhone and that you needed to get a cradle, I laughed. Seriously... what a half baked idea. If the iPhone 5 that comes out at the end of the year (with a rumored change in connection pins), the cradle will be useless to anyone that wants to upgrade to the new iPhone. Of course BMW will probably release a new cradle for $275!
Regular bluetooth is good cos it's universal and I think it'll be here for a while. Every phone uses it. But the Apps. Nope. I seriously doubt BMW is going to keep up with updating the apps as new Apple hardware/software becomes available. Heck, they could barely do a good job right now.
So basically.... If you're tech savvy, you'll probably want it. Ironically, if you ARE tech savvy, you'll be utterly disappointed in it.