I do use it alot really. I like to listen to Pandora most of the time so I have it docked. I do find myself forgetting the phone in the car often though. It would be nice if it beeped when I shut the car off or something.
I do like it better than the cable as it is much easier to dock and undock. I can do that with one hand vs. needing two for the cable.
One thing I wish was different was if I could get my text messages on the iDrive. It is annoying to have to open the armrest and look down to see when the message was. I don't get many texts though so it isn't too big of a deal.