Car computers can be frustrating.
I deal with that often as I insist on using linux, period, and frontends and mapping software are both in short supply and limited in ways. (Though NGhost and LinuxICE get better all the time!)
I've had mine in my car for about a year now and it still is not JUST the way I want it.
And it may never be.
Nobody (well, few folks anyway, lol) will think less of you if you give up on it. It is not for everybody.
It's a niche market, just like overclocking, watercooling and even my os of choice, linux.
If it isn't something that you enjoy, screw it man! Get the head unit and be happy.
For the pure functionality I myself need, I know I would be better off with a Garmin and a good head unit.
But I still enjoy my car computer.
And I like the extra stuff I can do with it beyond the basic functions.
But I would suggest you hold off on junking all the work you've done so for immediately- give it a bit of time before you make the decision final and spend any money or sell anything off.