The Nexus GSM fits perfectly in it. It is different from my previous HTC dock. It uses the Pogo pins on the side of the phone to charge the phone rather than the USB connector. I guess in the long run this increases the longevity of the connector. Also it comes with a car charger so you don't need to buy a separate one. The cable is not coiled though.
When you dock the phone, the phone switches to Car Home mode. I guess that's another function for those Pogo pins. However, unlike Gingerbread there is no Car Home app in Jelly Bean, for some reason Google took it out when they moved to ICS and this continues to be true. So either you flash the Car Home .apk from Gingerbread (look in XDA) or you download Car Home Ultra from Google Play.
The car dock charges the phone at AC speed rather than USB speed.
I got the 2000 mAh OEM extended battery that Samsung made for the Galaxy Nexus in South Korea to replace the 1750 mAh battery that comes with the phone from www.expansys.com
It has a 1 mm or so thicker back cover but increases battery life. I can go now over a day and still have 20 - 30 % left. The grip is actually better than the thinner cover as it follows the outline of the sides of the phone. The good news is that the extended 2000 mAh battery fits in the car dock, for those who are interested to get one.
I decided to fix the car dock on the left bottom side of the front windshield. This leaves the middle area of the glass open as it helps while driving. It also gets the phone close to my hand for accessing quick functions.