My car has the park distance control and I wish it had the rear camera. Top down seemed to me to be a gimmick.
Hyundai's have free cameras on the new cars and bmw wanted an additional $700.. What a rip off. Anyway, I got a quote to install (third party) the bmw rear only camera. I'll post the quote when I find the email. EDIT: $1250 from http://www.bimmer-tech.net/
That was price including shipping but bimmer-tech did not respond to my enquiry about installation instructions and coding. I wasn't about to drop a grand on the parts only to find out I had to spend another grand on installation and coding.