It's worth it.
Actually I would say that the setup is quite similar as far as work goes.
Sat radio:
Mount radio.
Mount sat antenna to car roof and route it into the car.
Plug radio to cigarette lighter.
Plug radio to car stereo.
Internet radio:
Mount iPod Touch.
Place EVDO router with the broadband card connected on the rear package tray.
Plug router to cigarette lighter.
Plug iPod Touch to cigarette lighter.
Plug iPod Touch to car stereo.
This requires two things to be plugged in for power vs. sat radio of only one.
Just some other things id throw out there.
Sat radio is ready to go after about 2 seconds after you power it on.
Internet radio is ready to go after about 15-20 seconds after you power up the router.
Sat radio costs $12.95 per month plus the cost of hardware which can be as cheap as $20 to as high as $400.
Internet radio in the car costs $60 per month plus the cost of hardware which can be $500. (Less expensive if you use a mobile phone since you will not need a router or iPod Touch but still something like $200).
Sat radio is cheaper and easier than internet radio for the car. But like I said earlier, it's worth it

(to me)