Didnt like route66, or destinator
Route 66 is for smart phones. Great for phones, but i would prefer a real touchscreen based system for a car.
Destinator is personally ugly and cumbersome. the maps look terrible to me. Without modding it with mapmonkey? or freedrive its practically unusable.
Streets and Trips and map point is OK, i like it's map and some of its usage, I like that it updates construction information. But its not touchscreen friendly, it's not really a program designed for giving directions with gps, it was designed first and foremost as a charting program. You sit down, you plot your drive and then get the directions. Road Runner Skins make it more touch friendly but compared to iguidance its still lacking in that.
CoPilot I really liked, I havent used it in the car since I only played with it at a friend house. It's alittle expensive ($150) but I liked the interface and map look. I'd have to try it out in my car to see if its really worth a damn. Screenshots of it here
http://www.alk.com/copilot/laptop_screenshots.asp
I do plan on testing it in my car sometime soon. Shame not more people do. The latest version seemed great. The previous ones I havent played with much as copilot always seemed like a handheld palm/pocketpc type of program.
Iguidance is current king here, and for good reason. Version 3 brought about a fantastic display mode for carpc/umpcs which works really well on a small screen. The menus are easy to navigate and control. It supports auto route and voice control, the voice it includes is actually really nice. With each release it seems more and more as if it will become the defacto gps program for carpcs. There is no SDK available. But people have modified iGuidance just fine by using reshacker.