The car kit is supposed to allow any iPhone GPS app to work with it, so you're not limited to the Magellan app. It works in portrait or landscape mode, and has a speaker for hearing directions and also link to your iPhone for Bluetooth based calls.
The Magellan Roadmate app itself [iTunes link] has a boatload of good features, and we're anxious to get our hands on the app for a full test. Holiday travelers will have a lot of good choices for navigating to your destinations. Remember when we thought the plain old Google Maps app was cool?
Thanks to Rich for the tip.