Was able to install the car kit today, went pretty smooth since I had a car kit installed previously (Nokia). I was able to use the same speaker and microphone that was installed, those plugged right in. The rest of the wiring used the same colors as the Nokia kit so it was pretty simple.
The instructions with the kit are not that great, but you can make it out. If you have done car stereo or this type of thing before you should have no problem, otherwise bring it to someone that does this and it should not be an issue.
So far, seems to work just fine. You do have to plug and unplug the wire on the side each time you want to use it, but that's not a big deal. It's also an issue that the BB has in general, not this kit.
Pictures of it installed (along with my old car kit) can be found at http://www.pauley.org/gs400